diff --git a/build.zig b/build.zig
index d7effb26..9f627169 100644
--- a/build.zig
+++ b/build.zig
@@ -112,6 +112,33 @@ pub fn build(b: *Build) !void {
         test_step.dependOn(&run_tests.step);
     }
 
+    {
+        // ZIGDOM
+        // browser
+        const exe = b.addExecutable(.{
+            .name = "legacy_test",
+            .use_llvm = true,
+            .root_module = b.createModule(.{
+                .root_source_file = b.path("src/main_legacy_test.zig"),
+                .target = target,
+                .optimize = optimize,
+                .sanitize_c = enable_csan,
+                .sanitize_thread = enable_tsan,
+                .imports = &.{
+                  .{.name = "lightpanda", .module = lightpanda_module},
+                },
+            }),
+        });
+        b.installArtifact(exe);
+
+        const run_cmd = b.addRunArtifact(exe);
+        if (b.args) |args| {
+            run_cmd.addArgs(args);
+        }
+        const run_step = b.step("legacy_test", "Run the app");
+        run_step.dependOn(&run_cmd.step);
+    }
+
     {
         // wpt
         const exe = b.addExecutable(.{
diff --git a/src/browser/js/Context.zig b/src/browser/js/Context.zig
index 5b6b510b..72ce1bef 100644
--- a/src/browser/js/Context.zig
+++ b/src/browser/js/Context.zig
@@ -615,6 +615,8 @@ pub fn mapZigInstanceToJs(self: *Context, js_obj_: ?v8.Object, value: anytype) !
             }
 
             const isolate = self.isolate;
+            const JsApi = bridge.Struct(ptr.child).JsApi;
+
             // Sometimes we're creating a new v8.Object, like when
             // we're returning a value from a function. In those cases
             // we have to get the object template, and we can get an object
@@ -626,19 +628,26 @@ pub fn mapZigInstanceToJs(self: *Context, js_obj_: ?v8.Object, value: anytype) !
                 const template = self.templates[resolved.class_id];
                 break :blk template.getInstanceTemplate().initInstance(v8_context);
             };
-            const JsApi = bridge.Struct(ptr.child).JsApi;
 
-            // The TAO contains the pointer to our Zig instance as
-            // well as any meta data we'll need to use it later.
-            // See the TaggedAnyOpaque struct for more details.
-            const tao = try arena.create(TaggedAnyOpaque);
-            tao.* = .{
-                .value = resolved.ptr,
-                .prototype_chain = resolved.prototype_chain.ptr,
-                .prototype_len = @intCast(resolved.prototype_chain.len),
-                .subtype = if (@hasDecl(JsApi.Meta, "subtype")) JsApi.Meta.subype else .node,
-            };
-            js_obj.setInternalField(0, v8.External.init(isolate, tao));
+            if (!@hasDecl(JsApi.Meta, "empty_with_no_proto")) {
+                // The TAO contains the pointer to our Zig instance as
+                // well as any meta data we'll need to use it later.
+                // See the TaggedAnyOpaque struct for more details.
+                const tao = try arena.create(TaggedAnyOpaque);
+                tao.* = .{
+                    .value = resolved.ptr,
+                    .prototype_chain = resolved.prototype_chain.ptr,
+                    .prototype_len = @intCast(resolved.prototype_chain.len),
+                    .subtype = if (@hasDecl(JsApi.Meta, "subtype")) JsApi.Meta.subype else .node,
+                };
+                js_obj.setInternalField(0, v8.External.init(isolate, tao));
+            } else {
+                // If the struct is empty, we don't need to do all
+                // the TOA stuff and setting the internal data.
+                // When we try to map this from JS->Zig, in
+                // typeTaggedAnyOpaque, we'll also know there that
+                // the type is empty and can create an empty instance.
+            }
 
             const js_persistent = PersistentObject.init(isolate, js_obj);
             gop.value_ptr.* = js_persistent;
@@ -1504,6 +1513,15 @@ pub fn typeTaggedAnyOpaque(comptime R: type, js_obj: v8.Object) !R {
     }
 
     const T = ti.pointer.child;
+    const JsApi = bridge.Struct(T).JsApi;
+
+    if (@hasDecl(JsApi.Meta, "empty_with_no_proto")) {
+        // Empty structs aren't stored as TOAs and there's no data
+        // stored in the JSObject's IntenrnalField. Why bother when
+        // we can just return an empty struct here?
+        return @constCast(@as(*const T, &.{}));
+    }
+
     // if it isn't an empty struct, then the v8.Object should have an
     // InternalFieldCount > 0, since our toa pointer should be embedded
     // at index 0 of the internal field count.
@@ -1511,7 +1529,7 @@ pub fn typeTaggedAnyOpaque(comptime R: type, js_obj: v8.Object) !R {
         return error.InvalidArgument;
     }
 
-    const type_name = @typeName(bridge.Struct(T).JsApi);
+    const type_name = @typeName(JsApi);
     if (@hasField(bridge.JsApiLookup, type_name) == false) {
         @compileError("unknown Zig type: " ++ @typeName(R));
     }
diff --git a/src/browser/js/Env.zig b/src/browser/js/Env.zig
index 71bed313..d75afd4b 100644
--- a/src/browser/js/Env.zig
+++ b/src/browser/js/Env.zig
@@ -314,7 +314,9 @@ fn generateConstructor(comptime JsApi: type, isolate: v8.Isolate) v8.FunctionTem
     };
 
     const template = v8.FunctionTemplate.initCallback(isolate, callback);
-    template.getInstanceTemplate().setInternalFieldCount(1);
+    if (!@hasDecl(JsApi.Meta, "empty_with_no_proto")) {
+        template.getInstanceTemplate().setInternalFieldCount(1);
+    }
     const class_name = v8.String.initUtf8(isolate, if (@hasDecl(JsApi.Meta, "name")) JsApi.Meta.name else @typeName(JsApi));
     template.setClassName(class_name);
     return template;
diff --git a/src/browser/tests/domparser.html b/src/browser/tests/domparser.html
index 390f7bfe..66014388 100644
--- a/src/browser/tests/domparser.html
+++ b/src/browser/tests/domparser.html
@@ -1,13 +1,13 @@
 <!DOCTYPE html>
 <script src="testing.js"></script>
 
-<!-- <script id=basic>
+<script id=basic>
 {
   const parser = new DOMParser();
   testing.expectEqual('object', typeof parser);
   testing.expectEqual('function', typeof parser.parseFromString);
 }
-</script> -->
+</script>
 
 <script id=parseSimpleHTML>
 {
@@ -23,7 +23,7 @@
 }
 </script>
 
-<!-- <script id=parseWithAttributes>
+<script id=parseWithAttributes>
 {
   const parser = new DOMParser();
   const doc = parser.parseFromString('<div id="test" class="foo">Content</div>', 'text/html');
@@ -118,4 +118,3 @@
   });
 }
 </script>
- -->
diff --git a/src/browser/tests/legacy/browser.html b/src/browser/tests/legacy/browser.html
new file mode 100644
index 00000000..1f60488b
--- /dev/null
+++ b/src/browser/tests/legacy/browser.html
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<script src="testing.js"></script>
+<script id=intl>
+  var te = new TextEncoder();
+  testing.expectEqual('utf-8', te.encoding);
+  testing.expectEqual([226, 130, 172], Array.from(te.encode('€')));
+
+  // this will crash if ICU isn't properly configured / ininitialized
+  testing.expectEqual("[object Intl.DateTimeFormat]", new Intl.DateTimeFormat().toString());
+</script>
diff --git a/src/browser/tests/legacy/crypto.html b/src/browser/tests/legacy/crypto.html
new file mode 100644
index 00000000..f1dc291a
--- /dev/null
+++ b/src/browser/tests/legacy/crypto.html
@@ -0,0 +1,26 @@
+<!DOCTYPE html>
+<script src="testing.js"></script>
+<script id=crypto>
+  const a = crypto.randomUUID();
+  const b = crypto.randomUUID();
+  testing.expectEqual(36, a.length);
+  testing.expectEqual(36, b.length);
+  testing.expectEqual(false, a == b)
+
+  testing.expectError('Error: QuotaExceededError', () => {
+    crypto.getRandomValues(new BigUint64Array(8193));
+  });
+
+  let r1 = new Int32Array(5)
+  let r2 = crypto.getRandomValues(r1)
+  testing.expectEqual(5, new Set(r1).size);
+  testing.expectEqual(5, new Set(r2).size);
+  testing.expectEqual(true, r1.every((v, i) => v === r2[i]));
+
+  var r3 = new Uint8Array(16);
+  let r4 = crypto.getRandomValues(r3);
+
+  r4[6] = 10;
+  testing.expectEqual(10, r4[6]);
+  testing.expectEqual(10, r3[6]);
+</script>
diff --git a/src/browser/tests/legacy/css.html b/src/browser/tests/legacy/css.html
new file mode 100644
index 00000000..3f83e934
--- /dev/null
+++ b/src/browser/tests/legacy/css.html
@@ -0,0 +1,6 @@
+<!DOCTYPE html>
+<script src="testing.js"></script>
+<script id=support>
+  testing.expectEqual(true, CSS.supports('display: flex'));
+  testing.expectEqual(true, CSS.supports('text-decoration-style', 'blink'));
+</script>
diff --git a/src/browser/tests/legacy/cssom/css_rule_list.html b/src/browser/tests/legacy/cssom/css_rule_list.html
new file mode 100644
index 00000000..577781e4
--- /dev/null
+++ b/src/browser/tests/legacy/cssom/css_rule_list.html
@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=css_rule_list>
+  let list = new CSSRuleList();
+  testing.expectEqual(true, list instanceof CSSRuleList);
+  testing.expectEqual(0, list.length);
+  testing.expectEqual(null, list.item(0));
+</script>
diff --git a/src/browser/tests/legacy/cssom/css_style_declaration.html b/src/browser/tests/legacy/cssom/css_style_declaration.html
new file mode 100644
index 00000000..ee4d3cd9
--- /dev/null
+++ b/src/browser/tests/legacy/cssom/css_style_declaration.html
@@ -0,0 +1,102 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=css_style_declaration>
+  let style = document.createElement('div').style;
+  style.cssText = 'color: red; font-size: 12px; margin: 5px !important;';
+  testing.expectEqual(3, style.length);
+
+  testing.expectEqua;('red', style.getPropertyValue('color'));
+  testing.expectEqua;('12px', style.getPropertyValue('font-size'));
+  testing.expectEqua;('', style.getPropertyValue('unknown-property'));
+
+  testing.expectEqual('important', style.getPropertyPriority('margin'));
+  testing.expectEqual('', style.getPropertyPriority('color'));
+  testing.expectEqual('', style.getPropertyPriority('unknown-property'));
+
+  testing.expectEqual('color', style.item(0));
+  testing.expectEqual('font-size', style.item(1));
+  testing.expectEqual('margin', style.item(2));
+  testing.expectEqual('', style.item(3));
+
+  style.setProperty('background-color', 'blue');
+  testing.expectEqual('blue', style.getPropertyValue('background-color'));
+  testing.expectEqual(4, style.length);
+
+  style.setProperty('color', 'green');
+  testing.expectEqual('green', style.color);
+  testing.expectEqual('green', style.getPropertyValue('color'));
+  testing.expectEqual(4, style.length);
+
+  style.setProperty('padding', '10px', 'important');
+  testing.expectEqual('10px', style.getPropertyValue('padding'));
+  testing.expectEqual('important', style.getPropertyPriority('padding'));
+
+  style.setProperty('border', '1px solid black', 'IMPORTANT');
+  testing.expectEqual('important', style.getPropertyPriority('border'));
+</script>
+
+<script id=removeProperty>
+  testing.expectEqual('green', style.removeProperty('color'));
+  testing.expectEqual('', style.getPropertyValue('color'));
+  testing.expectEqual(5, style.length)
+
+  testing.expectEqual('', style.removeProperty('unknown-property'));
+</script>
+
+<script id=includes>
+  testing.expectEqual(false, style.cssText.includes('font-size: 10px;'));
+  testing.expectEqual(true, style.cssText.includes('font-size: 12px;'));
+  testing.expectEqual(true, style.cssText.includes('margin: 5px !important;'));
+  testing.expectEqual(true, style.cssText.includes('padding: 10px !important;'));
+  testing.expectEqual(true, style.cssText.includes('border: 1px solid black !important;'));
+</script>
+
+<script id=special_char">
+  style.cssText = 'color: purple; text-align: center;';
+  testing.expectEqual(2, style.length);
+  testing.expectEqual('purple', style.getPropertyValue('color'));
+  testing.expectEqual('center', style.getPropertyValue('text-align'));
+  testing.expectEqual('', style.getPropertyValue('font-size'));
+
+  style.setProperty('cont', 'Hello; world!');
+  testing.expectEqual('Hello; world!', style.getPropertyValue('cont'));
+
+  style.cssText = 'content: "Hello; world!"; background-image: url("test.png");';
+  testing.expectEqual('"Hello; world!"', style.getPropertyValue('content'));
+  testing.expectEqual('url("test.png")', style.getPropertyValue('background-image'));
+</script>
+
+<script id=cssFloat">
+  testing.expectEqual('', style.cssFloat);
+  style.cssFloat = 'left';
+  testing.expectEqual('left', style.cssFloat);
+  testing.expectEqual('left', style.getPropertyValue('float'));
+
+  style.cssFloat = 'right';
+  testing.expectEqual('right', style.cssFloat);
+  testing.expectEqual('right', style.getPropertyValue('float'));
+
+  style.cssFloat = null;
+  testing.expectEqual('', style.cssFloat);
+  testing.expectEqual('', style.getPropertyValue('float'));
+</script>
+
+<script id=misc>
+  style.setProperty('display', '');
+  testing.expectEqual('', style.getPropertyValue('display'));
+
+  style.cssText = '  color  :  purple  ;  margin  :  10px  ;  ';
+  testing.expectEqual('purple', style.getPropertyValue('color'));
+  testing.expectEqual('10px', style.getPropertyValue('margin'));
+
+  style.setProperty('border-bottom-left-radius', '5px');
+  testing.expectEqual('5px', style.getPropertyValue('border-bottom-left-radius'));
+
+  testing.expectEqual('visible', style.visibility);
+  testing.expectEqual('visible', style.getPropertyValue('visibility'));
+
+  testing.expectEqual('10px', style.margin);
+  style.margin = 'auto';
+  testing.expectEqual('auto', style.margin);
+</script>
+
diff --git a/src/browser/tests/legacy/cssom/css_stylesheet.html b/src/browser/tests/legacy/cssom/css_stylesheet.html
new file mode 100644
index 00000000..223ee2cd
--- /dev/null
+++ b/src/browser/tests/legacy/cssom/css_stylesheet.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=css_stylesheet>
+  let css = new CSSStyleSheet()
+  testing.expectEqual(true, css instanceof CSSStyleSheet);
+  testing.expectEqual(0, css.cssRules.length);
+  testing.expectEqual(null, css.ownerRule);
+
+  let index1 = css.insertRule('body { color: red; }', 0);
+  testing.expectEqual(0, index1);
+  testing.expectEqual(1, css.cssRules.length);
+
+  let replaced = false;
+  css.replace('body{}').then(() => replaced = true);
+  testing.eventually(() => testing.expectEqual(true, replaced));
+</script>
diff --git a/src/browser/tests/legacy/dom/animation.html b/src/browser/tests/legacy/dom/animation.html
new file mode 100644
index 00000000..27e562a0
--- /dev/null
+++ b/src/browser/tests/legacy/dom/animation.html
@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=animation>
+  let a1 = document.createElement('div').animate(null, null);
+  testing.expectEqual('finished', a1.playState);
+
+  let cb = [];
+  a1.ready.then(() => { cb.push('ready') });
+  a1.finished.then((x) => {
+    cb.push('finished');
+    cb.push(x == a1);
+  });
+  testing.eventually(() => testing.expectEqual(['finished', true], cb));
+</script>
diff --git a/src/browser/tests/legacy/dom/attribute.html b/src/browser/tests/legacy/dom/attribute.html
new file mode 100644
index 00000000..2e208861
--- /dev/null
+++ b/src/browser/tests/legacy/dom/attribute.html
@@ -0,0 +1,33 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<a id="link" href="foo" class="ok">OK</a>
+
+<script id=attribute>
+  let a = document.createAttributeNS('foo', 'bar');
+  testing.expectEqual('foo', a.namespaceURI);
+  testing.expectEqual(null, a.prefix);
+  testing.expectEqual('bar', a.localName);
+  testing.expectEqual('bar', a.name);
+  testing.expectEqual('', a.value);
+
+  // TODO: libdom has a bug here: the created attr has no parent, it
+  // causes a panic w/ libdom when setting the value.
+  //.{ "a.value = 'nok'", "nok" },
+  testing.expectEqual(null, a.ownerElement);
+
+  let b = document.getElementById('link').getAttributeNode('class');
+  testing.expectEqual('class', b.name);
+  testing.expectEqual('ok', b.value);
+
+  b.value = 'nok';
+  testing.expectEqual('nok', b.value)
+
+  b.value = null;
+  testing.expectEqual('null', b.value);
+
+  b.value = 'ok';
+  testing.expectEqual('ok', b.value);
+
+  testing.expectEqual('link', b.ownerElement.id);
+</script>
diff --git a/src/browser/tests/legacy/dom/character_data.html b/src/browser/tests/legacy/dom/character_data.html
new file mode 100644
index 00000000..ff74da90
--- /dev/null
+++ b/src/browser/tests/legacy/dom/character_data.html
@@ -0,0 +1,48 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<a id="link" href="foo" class="ok">OK</a>
+
+<script id=character_data>
+  let link = document.getElementById('link');
+  let cdata = link.firstChild;
+  testing.expectEqual('OK', cdata.data);
+
+  cdata.data = 'OK modified';
+  testing.expectEqual('OK modified', cdata.data);
+  cdata.data = 'OK';
+
+  testing.expectEqual(2, cdata.length);
+
+  testing.expectEqual(true, cdata.nextElementSibling === null);
+
+  // create a next element
+  let next = document.createElement('a');
+  testing.expectEqual(true, link.appendChild(next, cdata) !== undefined);
+  testing.expectEqual(true, cdata.nextElementSibling.localName === 'a');
+
+  testing.expectEqual(true, cdata.previousElementSibling === null);
+
+  // create a prev element
+  let prev = document.createElement('div');
+  testing.expectEqual(true, link.insertBefore(prev, cdata) !== undefined);
+  testing.expectEqual('div', cdata.previousElementSibling.localName);
+
+  cdata.appendData(' modified');
+  testing.expectEqual('OK modified', cdata.data);
+
+  cdata.deleteData('OK'.length, ' modified'.length);
+  testing.expectEqual('OK', cdata.data)
+
+  cdata.insertData('OK'.length-1, 'modified');
+  testing.expectEqual('OmodifiedK', cdata.data);
+
+  cdata.replaceData('OK'.length-1, 'modified'.length, 'replaced');
+  testing.expectEqual('OreplacedK', cdata.data);
+
+  testing.expectEqual('replaced', cdata.substringData('OK'.length-1, 'replaced'.length));
+  testing.expectEqual('', cdata.substringData('OK'.length-1, 0));
+
+  testing.expectEqual('replaced', cdata.substringData('OK'.length-1, 'replaced'.length));
+  testing.expectEqual('', cdata.substringData('OK'.length-1, 0));
+</script>
diff --git a/src/browser/tests/legacy/dom/comment.html b/src/browser/tests/legacy/dom/comment.html
new file mode 100644
index 00000000..2f87846c
--- /dev/null
+++ b/src/browser/tests/legacy/dom/comment.html
@@ -0,0 +1,9 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=comment>
+  let comment = new Comment('foo');
+  testing.expectEqual('foo', comment.data);
+
+  let empty = new Comment()
+  testing.expectEqual('', empty.data);
+</script>
diff --git a/src/browser/tests/legacy/dom/document.html b/src/browser/tests/legacy/dom/document.html
new file mode 100644
index 00000000..950daaab
--- /dev/null
+++ b/src/browser/tests/legacy/dom/document.html
@@ -0,0 +1,190 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<div id="content">
+  <a id="a1" href="foo" class="ok">OK</a>
+  <p id="p1" class="ok empty">
+    <span id="s1"></span>
+  </p>
+  <p id="p2"> And</p>
+</div>
+
+<script id=document>
+  testing.expectEqual('Document', document.__proto__.__proto__.constructor.name);
+  testing.expectEqual('Node', document.__proto__.__proto__.__proto__.constructor.name);
+  testing.expectEqual('EventTarget', document.__proto__.__proto__.__proto__.__proto__.constructor.name);
+
+  let newdoc = new Document();
+  testing.expectEqual(null, newdoc.documentElement);
+  testing.expectEqual(0, newdoc.children.length);
+  testing.expectEqual(0, newdoc.getElementsByTagName('*').length);
+  testing.expectEqual(null, newdoc.getElementsByTagName('*').item(0));
+  testing.expectEqual(true, newdoc.inputEncoding === document.inputEncoding);
+  testing.expectEqual(true, newdoc.documentURI === document.documentURI);
+  testing.expectEqual(true, newdoc.URL === document.URL);
+  testing.expectEqual(true, newdoc.compatMode === document.compatMode);
+  testing.expectEqual(true, newdoc.characterSet === document.characterSet);
+  testing.expectEqual(true, newdoc.charset === document.charset);
+  testing.expectEqual(true, newdoc.contentType === document.contentType);
+
+  testing.expectEqual('HTML', document.documentElement.tagName);
+
+  testing.expectEqual('UTF-8', document.characterSet);
+  testing.expectEqual('UTF-8', document.charset);
+  testing.expectEqual('UTF-8', document.inputEncoding);
+  testing.expectEqual('CSS1Compat', document.compatMode);
+  testing.expectEqual('text/html', document.contentType);
+
+  testing.expectEqual('http://localhost:9582/src/tests/dom/document.html', document.documentURI);
+  testing.expectEqual('http://localhost:9582/src/tests/dom/document.html', document.URL);
+
+  testing.expectEqual(document.body, document.activeElement);
+
+  $('#a1').focus();
+  testing.expectEqual($('#a1'), document.activeElement);
+
+  testing.expectEqual(0, document.styleSheets.length);
+</script>
+
+<script id=getElementById>
+  let divById = document.getElementById('content');
+  testing.expectEqual('HTMLDivElement', divById.constructor.name);
+  testing.expectEqual('div', divById.localName);
+</script>
+
+<script id=getElementsByTagName>
+  let byTagName = document.getElementsByTagName('p');
+  testing.expectEqual(2, byTagName.length)
+  testing.expectEqual('p1', byTagName.item(0).id);
+  testing.expectEqual('p2', byTagName.item(1).id);
+
+  let byTagNameAll = document.getElementsByTagName('*');
+  // If you add a script block (or change the HTML in any other way on this
+  // page), this test will break. Adjust it accordingly.
+  testing.expectEqual(21, byTagNameAll.length);
+  testing.expectEqual('html', byTagNameAll.item(0).localName);
+  testing.expectEqual('SCRIPT', byTagNameAll.item(11).tagName);
+
+  testing.expectEqual('s1', byTagNameAll.namedItem('s1').id);
+</script>
+
+<script id=getElementByClassName>
+  let ok = document.getElementsByClassName('ok');
+  testing.expectEqual(2, ok.length);
+
+  let empty = document.getElementsByClassName('empty');
+  testing.expectEqual(1, empty.length);
+
+  let emptyok = document.getElementsByClassName('empty ok');
+  testing.expectEqual(1, emptyok.length);
+</script>
+
+<script id=createXYZ>
+  var v = document.createDocumentFragment();
+  testing.expectEqual('#document-fragment', v.nodeName);
+
+  v = document.createTextNode('foo');
+  testing.expectEqual('#text', v.nodeName);
+
+  v = document.createCDATASection('foo');
+  testing.expectEqual('#cdata-section', v.nodeName);
+
+  v = document.createAttribute('foo');
+  testing.expectEqual('foo', v.nodeName);
+
+  v = document.createComment('foo');
+  testing.expectEqual('#comment', v.nodeName);
+  v.cloneNode(); // doesn't crash, (I guess that's the point??)
+
+  let pi = document.createProcessingInstruction('foo', 'bar')
+  testing.expectEqual('foo', pi.target);
+  pi.cloneNode(); // doesn't crash (I guess that's the point??)
+</script>
+
+<script id=importNode>
+  let nimp = document.getElementById('content');
+  var v = document.importNode(nimp);
+  testing.expectEqual('DIV', v.nodeName);
+</script>
+
+<script id=children>
+  testing.expectEqual(1, document.children.length);
+  testing.expectEqual('HTML', document.children.item(0).nodeName);
+  testing.expectEqual('HTML', document.firstElementChild.nodeName);
+  testing.expectEqual('HTML', document.lastElementChild.nodeName);
+  testing.expectEqual(1, document.childElementCount);
+
+  let nd = new Document();
+  testing.expectEqual(0, nd.children.length);
+  testing.expectEqual(null, nd.children.item(0));
+  testing.expectEqual(null, nd.firstElementChild);
+  testing.expectEqual(null, nd.lastElementChild);
+  testing.expectEqual(0, nd.childElementCount);
+</script>
+
+<script id=createElement>
+  let emptydoc = document.createElement('html');
+  emptydoc.prepend(document.createElement('html'));
+
+  let emptydoc2 = document.createElement('html');
+  emptydoc2.append(document.createElement('html'));
+
+  // Not sure what the above are testing, I just copied and pasted them.
+  // Maybe that something doesn't crash?
+  // Adding this so that the test runner doesn't complain;
+  testing.skip();
+</script>
+
+<script id=querySelector>
+  testing.expectEqual(null, document.querySelector(''));
+  testing.expectEqual('HTML', document.querySelector('*').nodeName);
+  testing.expectEqual('content', document.querySelector('#content').id);
+  testing.expectEqual('p1', document.querySelector('#p1').id);
+  testing.expectEqual('a1', document.querySelector('.ok').id);
+  testing.expectEqual('p1', document.querySelector('a ~ p').id);
+  testing.expectEqual('HTML', document.querySelector(':root').nodeName);
+
+  testing.expectEqual(2, document.querySelectorAll('p').length);
+
+  testing.expectEqual([''],
+    Array.from(document.querySelectorAll('#content > p#p1'))
+        .map(row => row.querySelector('span').textContent)
+  );
+
+  testing.expectEqual(0, document.querySelectorAll('.\\:popover-open').length);
+  testing.expectEqual(0, document.querySelectorAll('.foo\\:bar').length);
+</script>
+
+<script id=adoptNode>
+// this test breaks the doc structure, keep it at the end
+  let nadop = document.getElementById('content')
+  var v = document.adoptNode(nadop);
+  testing.expectEqual('DIV', v.nodeName);
+</script>
+
+<script id=adoptedStyleSheets>
+  const acss = document.adoptedStyleSheets;
+  testing.expectEqual(0, acss.length);
+  acss.push(new CSSStyleSheet());
+  testing.expectEqual(1, acss.length);
+</script>
+
+<script id=createEvent>
+    const event = document.createEvent("Event");
+
+    testing.expectEqual(true, event instanceof Event);
+    testing.expectEqual("", event.type);
+
+    const customEvent = document.createEvent("CustomEvent");
+    customEvent.initCustomEvent("hey", false, false);
+
+    testing.expectEqual(true, customEvent instanceof CustomEvent);
+    testing.expectEqual(true, customEvent instanceof Event);
+
+    testing.withError(
+        (err) => {
+            // TODO: Check the error type.
+        },
+        () => document.createEvent("InvalidType"),
+    );
+</script>
diff --git a/src/browser/tests/legacy/dom/document_fragment.html b/src/browser/tests/legacy/dom/document_fragment.html
new file mode 100644
index 00000000..ff02b3a4
--- /dev/null
+++ b/src/browser/tests/legacy/dom/document_fragment.html
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<body></body>
+
+<script id=documentFragement>
+  testing.expectEqual('DocumentFragment', new DocumentFragment().constructor.name);
+
+  const dc1 = new DocumentFragment();
+  testing.expectEqual(true, dc1.isEqualNode(dc1))
+
+  const dc2 = new DocumentFragment();
+  testing.expectEqual(true, dc1.isEqualNode(dc2))
+
+  let f = document.createDocumentFragment();
+  let d = document.createElement('div');
+  testing.expectEqual(0, d.childElementCount);
+
+  d.id = 'x';
+  testing.expectEqual(null, $('#x'));
+
+  f.append(d);
+  testing.expectEqual(1, f.childElementCount)
+  testing.expectEqual('x', f.children[0].id);
+  testing.expectEqual(null, $('#x'));
+
+  document.getElementsByTagName('body')[0].append(f.cloneNode(true));
+  testing.expectEqual(true, $('#x') != null);
+
+  testing.expectEqual(null, document.querySelector('.hello'));
+  testing.expectEqual(0, document.querySelectorAll('.hello').length);
+
+  testing.expectEqual('x', document.querySelector('#x').id);
+  testing.expectEqual(['x'], Array.from(document.querySelectorAll('#x')).map((n) => n.id));
+</script>
diff --git a/src/browser/tests/legacy/dom/document_type.html b/src/browser/tests/legacy/dom/document_type.html
new file mode 100644
index 00000000..ff7cdbc8
--- /dev/null
+++ b/src/browser/tests/legacy/dom/document_type.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=documentType>
+  let dt1 = document.implementation.createDocumentType('qname1', 'pid1', 'sys1');
+  let dt2 = document.implementation.createDocumentType('qname2', 'pid2', 'sys2');
+  let dt3 = document.implementation.createDocumentType('qname1', 'pid1', 'sys1');
+  testing.expectEqual(true, dt1.isEqualNode(dt1));
+  testing.expectEqual(true, dt1.isEqualNode(dt3));
+  testing.expectEqual(false, dt1.isEqualNode(dt2));
+  testing.expectEqual(false, dt2.isEqualNode(dt3));
+  testing.expectEqual(false, dt1.isEqualNode(document));
+  testing.expectEqual(false, document.isEqualNode(dt1));
+</script>
diff --git a/src/browser/tests/legacy/dom/dom_parser.html b/src/browser/tests/legacy/dom/dom_parser.html
new file mode 100644
index 00000000..bf9bec8a
--- /dev/null
+++ b/src/browser/tests/legacy/dom/dom_parser.html
@@ -0,0 +1,7 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=domParser>
+  const dp = new DOMParser();;
+  const parsed = dp.parseFromString('<div>abc</div>', 'text/html');
+  testing.expectEqual('[object HTMLDocument]', parsed.toString());
+</script>
diff --git a/src/browser/tests/legacy/dom/element.html b/src/browser/tests/legacy/dom/element.html
new file mode 100644
index 00000000..3255b7d2
--- /dev/null
+++ b/src/browser/tests/legacy/dom/element.html
@@ -0,0 +1,341 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<div id="content" dir="ltr">
+  <a id="link" href="foo" class="ok">OK</a>
+  <p id="para-empty" class="ok empty">
+    <span id="para-empty-child"></span>
+  </p>
+  <p id="para"> And</p>
+  <!--comment-->
+</div>
+
+<script id=element>
+  let content = document.getElementById('content');
+  testing.expectEqual('http://www.w3.org/1999/xhtml', content.namespaceURI);
+  testing.expectEqual(null, content.prefix);
+  testing.expectEqual('div', content.localName);
+  testing.expectEqual('DIV', content.tagName);
+  testing.expectEqual('content', content.id);
+  testing.expectEqual('ltr', content.dir);
+
+  content.id = 'foo';
+  testing.expectEqual('foo', content.id);
+
+  content.id = 'content';
+  testing.expectEqual('', content.className);
+
+  let p1 = document.getElementById('para-empty');
+  testing.expectEqual('ok empty', p1.className);
+  testing.expectEqual('', p1.dir);
+
+  p1.className = 'foo bar baz';
+  testing.expectEqual('foo bar baz', p1.className);
+
+  p1.className = 'ok empty';
+  testing.expectEqual(2, p1.classList.length);
+</script>
+
+<script id=closest>
+  const el2 = document.createElement('div');
+  el2.id = 'closest';
+  el2.className = 'ok';
+
+  testing.expectEqual(el2, el2.closest('#closest'));
+  testing.expectEqual(el2, el2.closest('.ok'));
+  testing.expectEqual(null, el2.closest('#9000'));
+  testing.expectEqual(null, el2.closest('.notok'));
+
+  const sp = document.createElement('span');
+  el2.appendChild(sp);
+  testing.expectEqual(el2, sp.closest('#closest'));
+  testing.expectEqual(null, sp.closest('#9000'));
+</script>
+
+<script id=attributes>
+  testing.expectEqual(true, content.hasAttributes());
+  testing.expectEqual(2, content.attributes.length);
+  testing.expectEqual(['id', 'dir'], content.getAttributeNames());
+  testing.expectEqual('content', content.getAttribute('id'));
+  testing.expectEqual('content', content.attributes['id'].value);
+
+  let x = '';
+  for (const attr of content.attributes) {
+    x += attr.name + '=' + attr.value + ',';
+  }
+  testing.expectEqual('id=content,dir=ltr,', x);
+
+  testing.expectEqual(false, content.hasAttribute('foo'));
+  testing.expectEqual(null, content.getAttribute('foo'));
+
+  content.setAttribute('foo', 'bar');
+  testing.expectEqual(true, content.hasAttribute('foo'));
+  testing.expectEqual('bar', content.getAttribute('foo'));
+  testing.expectEqual(['id', 'dir', 'foo'], content.getAttributeNames());
+
+  testing.expectError('Error: InvalidCharacterError', () => {
+    content.setAttribute('.foo', 'invalid')
+  });
+
+  content.setAttribute('foo', 'baz');
+  testing.expectEqual(true, content.hasAttribute('foo'));
+  testing.expectEqual('baz', content.getAttribute('foo'));
+
+  content.removeAttribute('foo');
+  testing.expectEqual(false, content.hasAttribute('foo'));
+  testing.expectEqual(null, content.getAttribute('foo'));
+
+  let b = document.getElementById('content');
+  testing.expectEqual(true, b.toggleAttribute('foo'));
+  testing.expectEqual(true, b.hasAttribute('foo'));
+  testing.expectEqual('', b.getAttribute('foo'));
+
+  testing.expectEqual(false, b.toggleAttribute('foo'));
+  testing.expectEqual(false, b.hasAttribute('foo'));
+
+  testing.expectEqual(false, document.createElement('a').hasAttributes());
+
+  const div2 = document.createElement('div');
+  div2.innerHTML = '<p id=1 .lit$id=9>a</p>';
+  testing.expectEqual('<p id="1" .lit$id="9">a</p>', div2.innerHTML);
+  testing.expectEqual(['id', '.lit$id'], div2.childNodes[0].getAttributeNames());
+</script>
+
+<script id=children>
+  testing.expectEqual(3, content.children.length);
+  testing.expectEqual('A', content.firstElementChild.nodeName);
+  testing.expectEqual('P', content.lastElementChild.nodeName);
+  testing.expectEqual(3, content.childElementCount);
+</script>
+
+<script id=sibling>
+  content.prepend(document.createTextNode('foo'));
+  content.append(document.createTextNode('bar'));
+
+  let d = document.getElementById('para');
+  testing.expectEqual('P', d.previousElementSibling.nodeName);
+  testing.expectEqual(null, d.nextElementSibling);
+</script>
+
+<script id=querySelector>
+  testing.expectEqual(null, content.querySelector('foo'));
+  testing.expectEqual(null, content.querySelector('#foo'));
+  testing.expectEqual('link', content.querySelector('#link').id);
+  testing.expectEqual('para', content.querySelector('#para').id);
+  testing.expectEqual('link', content.querySelector('*').id);
+  testing.expectEqual(null, content.querySelector(''));
+  testing.expectEqual('link', content.querySelector('*').id);
+  testing.expectEqual(null, content.querySelector('#content'));
+  testing.expectEqual('para', content.querySelector('#para').id);
+  testing.expectEqual('link', content.querySelector('.ok').id);
+  testing.expectEqual('para-empty', content.querySelector('a ~ p').id);
+
+  testing.expectEqual(0, content.querySelectorAll('foo').length);
+  testing.expectEqual(0, content.querySelectorAll('#foo').length);
+  testing.expectEqual(1, content.querySelectorAll('#link').length);
+  testing.expectEqual('link', content.querySelectorAll('#link').item(0).id);
+  testing.expectEqual(1, content.querySelectorAll('#para').length);
+  testing.expectEqual('para', content.querySelectorAll('#para').item(0).id);
+  testing.expectEqual(4, content.querySelectorAll('*').length);
+  testing.expectEqual(2, content.querySelectorAll('p').length);
+  testing.expectEqual('link', content.querySelectorAll('.ok').item(0).id);
+</script>
+
+<script id=createdAttributes>
+  let ff = document.createAttribute('foo');
+  content.setAttributeNode(ff);
+  testing.expectEqual('foo', content.getAttributeNode('foo').name);
+  testing.expectEqual('foo', content.removeAttributeNode(ff).name);
+  testing.expectEqual(null, content.getAttributeNode('bar'));
+</script>
+
+<script id=innerHTML>
+  testing.expectEqual(' And', document.getElementById('para').innerHTML);
+  testing.expectEqual('<span id="para-empty-child"></span>', $('#para-empty').innerHTML.trim());
+
+  let h = $('#para-empty');
+  const prev = h.innerHTML;
+  h.innerHTML = '<p id="hello">hello world</p>';
+  testing.expectEqual('<p id="hello">hello world</p>', h.innerHTML);
+  testing.expectEqual('P', h.firstChild.nodeName);
+  testing.expectEqual('hello', h.firstChild.id);
+  testing.expectEqual('hello world', h.firstChild.textContent);
+
+  h.innerHTML = prev;
+  testing.expectEqual('<span id="para-empty-child"></span>', $('#para-empty').innerHTML.trim());
+  testing.expectEqual('<p id="para"> And</p>', $('#para').outerHTML);
+</script>
+
+<script id=dimensions>
+  const para = document.getElementById('para');
+  testing.expectEqual(5, para.clientWidth);
+  testing.expectEqual(5, para.clientHeight);
+
+  let r1 = document.getElementById('para').getBoundingClientRect();
+  testing.expectEqual(0, r1.x);
+  testing.expectEqual(0, r1.y);
+  testing.expectEqual(5, r1.width);
+  testing.expectEqual(5, r1.height);
+
+  let r2 = document.getElementById('content').getBoundingClientRect();
+  testing.expectEqual(5, r2.x);
+  testing.expectEqual(0, r2.y);
+  testing.expectEqual(5, r2.width);
+  testing.expectEqual(5, r2.height);
+
+  let r3 = document.getElementById('para').getBoundingClientRect();
+  testing.expectEqual(0, r3.x);
+  testing.expectEqual(0, r3.y);
+  testing.expectEqual(5, r3.width);
+  testing.expectEqual(5, r3.height);
+
+  testing.expectEqual(10, para.clientWidth);
+  testing.expectEqual(5, para.clientHeight);
+
+  let r4 = document.createElement('div').getBoundingClientRect();
+  testing.expectEqual(0, r4.x);
+  testing.expectEqual(0, r4.y);
+  testing.expectEqual(0, r4.width);
+  testing.expectEqual(0, r4.height);
+</script>
+
+<script id=matches>
+  const el = document.createElement('div');
+  el.id = 'matches';
+  el.className = 'ok';
+  testing.expectEqual(true, el.matches('#matches'));
+  testing.expectEqual(true, el.matches('.ok'));
+  testing.expectEqual(false, el.matches('#9000'));
+  testing.expectEqual(false, el.matches('.notok'));
+</script>
+
+<script id=scroll>
+  const el3 = document.createElement('div');
+  el3.scrollIntoViewIfNeeded();
+  el3.scrollIntoViewIfNeeded(false);
+  // doesn't throw is good enough
+  testing.skip();
+</script>
+
+<script id=before>
+  const before_container = document.createElement('div');
+  document.append(before_container);
+
+  const b1 = document.createElement('div');
+  before_container.append(b1);
+
+  const b1_a = document.createElement('p');
+  b1.before(b1_a, 'over 9000');
+  testing.expectEqual('<p></p>over 9000<div></div>', before_container.innerHTML);
+</script>
+
+<script id=after>
+  const after_container = document.createElement('div');
+  document.append(after_container);
+  const a1 = document.createElement('div');
+  after_container.append(a1);
+
+  const a1_a = document.createElement('p');
+  a1.after('over 9000', a1_a);
+  testing.expectEqual('<div></div>over 9000<p></p>', after_container.innerHTML);
+</script>
+
+<script id=getElementsByTagName>
+  var div1 = document.createElement('div');
+  div1.innerHTML = "  <link/><table></table><a href='/a'>a</a><input type='checkbox'/>";
+  testing.expectEqual(1, div1.getElementsByTagName('a').length);
+</script>
+
+<script id=outerHTML>
+  let fc = document.createElement('div')
+  fc.innerHTML = '<script><\/script>';
+  testing.expectEqual('<div><script><\/script></div>', fc.outerHTML);
+
+  fc = document.createElement('div')
+  fc.innerHTML = '<script><\/script><p>hello</p>';
+  testing.expectEqual('<div><script><\/script><p>hello</p></div>', fc.outerHTML);
+</script>
+
+<script id=remove>
+  const rm = document.createElement('div');
+  testing.expectEqual([], rm.getAttributeNames());
+  rm.id = 'to-remove';
+
+  document.getElementsByTagName('body')[0].appendChild(rm);
+  $('#to-remove').remove();
+  testing.expectEqual(null, $('#to-remove'));
+</script>
+
+<script id=elementDir>
+  const divElement = document.createElement("div");
+  // Always initialized with empty string if `dir` attribute not provided.
+  testing.expectEqual("", divElement.dir);
+
+  divElement.dir = "ltr";
+  testing.expectEqual("ltr", divElement.dir);
+
+  divElement.dir = "rtl";
+  testing.expectEqual("rtl", divElement.dir);
+
+  divElement.dir = "auto";
+  testing.expectEqual("auto", divElement.dir);
+</script>
+
+<script id=linkRel>
+  const linkElement = document.createElement("link");
+  // A newly created link element must have it's rel set to empty string.
+  testing.expectEqual("", linkElement.rel);
+
+  linkElement.rel = "stylesheet";
+  testing.expectEqual("stylesheet", linkElement.rel);
+</script>
+
+<!-- This structure will get mutated by insertAdjacentHTML test -->
+<div id="insert-adjacent-html-outer-wrapper">
+    <div id="insert-adjacent-html-inner-wrapper">
+        <span></span>
+        <p>content</p>
+    </div>
+</div>
+
+<script id=insertAdjacentHTML>
+  // Insert "beforeend".
+  const wrapper = $("#insert-adjacent-html-inner-wrapper");
+  wrapper.insertAdjacentHTML("beforeend", "<h1>title</h1>");
+  let newElement = wrapper.lastElementChild;
+  testing.expectEqual("H1", newElement.tagName);
+  testing.expectEqual("title", newElement.innerText);
+
+  // Insert "beforebegin".
+  wrapper.insertAdjacentHTML("beforebegin", "<h2>small title</h2>");
+  newElement = wrapper.previousElementSibling;
+  testing.expectEqual("H2", newElement.tagName);
+  testing.expectEqual("small title", newElement.innerText);
+
+  // Insert "afterend".
+  wrapper.insertAdjacentHTML("afterend", "<div id=\"afterend\">after end</div>");
+  newElement = wrapper.nextElementSibling;
+  testing.expectEqual("DIV", newElement.tagName);
+  testing.expectEqual("after end", newElement.innerText);
+  testing.expectEqual("afterend", newElement.id);
+
+  // Insert "afterbegin".
+  wrapper.insertAdjacentHTML("afterbegin", "<div class=\"afterbegin\">after begin</div><yy></yy>");
+  newElement = wrapper.firstElementChild;
+  testing.expectEqual("DIV", newElement.tagName);
+  testing.expectEqual("after begin", newElement.innerText);
+  testing.expectEqual("afterbegin", newElement.className);
+</script>
+
+<script id=nonBreakingSpace>
+  // Test non-breaking space encoding (critical for React hydration)
+  const div = document.createElement('div');
+  div.innerHTML = 'hello\xa0world';
+  testing.expectEqual('hello\xa0world', div.textContent);
+  testing.expectEqual('hello&nbsp;world', div.innerHTML);
+
+  // Test that outerHTML also encodes non-breaking spaces correctly
+  const p = document.createElement('p');
+  p.textContent = 'XAnge\xa0Privacy';
+  testing.expectEqual('<p>XAnge&nbsp;Privacy</p>', p.outerHTML);
+</script>
diff --git a/src/browser/tests/legacy/dom/event_target.html b/src/browser/tests/legacy/dom/event_target.html
new file mode 100644
index 00000000..68fb8c6b
--- /dev/null
+++ b/src/browser/tests/legacy/dom/event_target.html
@@ -0,0 +1,116 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<div id="content"><p id=para></p></div>
+
+<script id=eventTarget>
+  testing.expectEqual('[object EventTarget]', new EventTarget().toString());
+
+  let content = $('#content');
+  let para = $('#para');
+
+  var nb = 0;
+  var evt;
+  var phase;
+  var cur;
+
+  function reset() {
+    nb = 0;
+    evt = undefined;
+    phase = undefined;
+    cur = undefined;
+  }
+
+  function cbk(event) {
+    evt = event;
+    phase = event.eventPhase;
+    cur = event.currentTarget;
+    nb++;
+  }
+
+  content.addEventListener('basic', cbk);
+  content.dispatchEvent(new Event('basic'));
+  testing.expectEqual(1, nb);
+  testing.expectEqual(true, evt instanceof Event);
+  testing.expectEqual('basic', evt.type);
+  testing.expectEqual(2, phase);
+  testing.expectEqual('content', cur.getAttribute('id'));
+
+  reset();
+  para.dispatchEvent(new Event('basic'))
+
+  // handler is not called, no capture, not the targeno bubbling
+  testing.expectEqual(0, nb);
+  testing.expectEqual(undefined, evt);
+
+  reset();
+  content.addEventListener('basic', cbk);
+  content.dispatchEvent(new Event('basic'))
+  testing.expectEqual(1, nb);
+
+  reset();
+  content.addEventListener('basic', cbk, true);
+  content.dispatchEvent(new Event('basic'));
+  testing.expectEqual(2, nb);
+
+  reset()
+  content.removeEventListener('basic', cbk);
+  content.dispatchEvent(new Event('basic'));
+  testing.expectEqual(1, nb);
+
+  reset();
+  content.removeEventListener('basic', cbk, {capture: true});
+  content.dispatchEvent(new Event('basic'));
+  testing.expectEqual(0, nb);
+
+  reset();
+  content.addEventListener('capture', cbk, true);
+  content.dispatchEvent(new Event('capture'));
+  testing.expectEqual(1, nb);
+  testing.expectEqual(true, evt instanceof Event);
+  testing.expectEqual('capture', evt.type);
+  testing.expectEqual(2, phase);
+  testing.expectEqual('content', cur.getAttribute('id'));
+
+  reset();
+  para.dispatchEvent(new Event('capture'));
+  testing.expectEqual(1, nb);
+  testing.expectEqual(true, evt instanceof Event);
+  testing.expectEqual('capture', evt.type);
+  testing.expectEqual(1, phase);
+  testing.expectEqual('content', cur.getAttribute('id'));
+
+  reset();
+  content.addEventListener('bubbles', cbk);
+  content.dispatchEvent(new Event('bubbles', {bubbles: true}));
+  testing.expectEqual(1, nb);
+  testing.expectEqual(true, evt instanceof Event);
+  testing.expectEqual('bubbles', evt.type);
+  testing.expectEqual(2, phase);
+  testing.expectEqual('content', cur.getAttribute('id'));
+
+  reset();
+  para.dispatchEvent(new Event('bubbles', {bubbles: true}));
+  testing.expectEqual(1, nb);
+  testing.expectEqual(true, evt instanceof Event);
+  testing.expectEqual('bubbles', evt.type);
+  testing.expectEqual(3, phase);
+  testing.expectEqual('content', cur.getAttribute('id'));
+
+
+  const obj1 = {
+    calls: 0,
+    handleEvent: function() { this.calls += 1 }
+  };
+  content.addEventListener('he', obj1);
+  content.dispatchEvent(new Event('he'));
+  testing.expectEqual(1, obj1.calls);
+
+  content.removeEventListener('he', obj1);
+  content.dispatchEvent(new Event('he'));
+  testing.expectEqual(1, obj1.calls);
+
+  // doesn't crash on null receiver
+  content.addEventListener('he2', null);
+  content.dispatchEvent(new Event('he2'));
+</script>
diff --git a/src/browser/tests/legacy/dom/exceptions.html b/src/browser/tests/legacy/dom/exceptions.html
new file mode 100644
index 00000000..c6bb91f1
--- /dev/null
+++ b/src/browser/tests/legacy/dom/exceptions.html
@@ -0,0 +1,40 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<div id="content">
+  <a id="link" href="foo" class="ok">OK</a>
+</div>
+
+<script id=exceptions>
+  let content = $('#content');
+  let link = $('#link');
+
+  testing.withError((err) => {
+    const msg = "Failed to execute 'appendChild' on 'Node': The new child element contains the parent.";
+    testing.expectEqual(3, err.code);
+    testing.expectEqual(msg, err.message);
+    testing.expectEqual('HierarchyRequestError: ' + msg, err.toString());
+    testing.expectEqual(true, err instanceof DOMException);
+    testing.expectEqual(true, err instanceof Error);
+  }, () => link.appendChild(content));
+</script>
+
+<script id=constructor>
+  let exc0 = new DOMException();
+  testing.expectEqual('Error', exc0.name);
+  testing.expectEqual(0, exc0.code);
+  testing.expectEqual('', exc0.message);
+  testing.expectEqual('Error', exc0.toString());
+
+  let exc1 = new DOMException('Sandwich malfunction');
+  testing.expectEqual('Error', exc1.name);
+  testing.expectEqual(0, exc1.code);
+  testing.expectEqual('Sandwich malfunction', exc1.message);
+  testing.expectEqual('Error: Sandwich malfunction', exc1.toString());
+
+  let exc2 = new DOMException('Caterpillar turned into a butterfly', 'NoModificationAllowedError');
+  testing.expectEqual('NoModificationAllowedError', exc2.name);
+  testing.expectEqual(7, exc2.code);
+  testing.expectEqual('Caterpillar turned into a butterfly', exc2.message);
+  testing.expectEqual('NoModificationAllowedError: Caterpillar turned into a butterfly', exc2.toString());
+</script>
diff --git a/src/browser/tests/legacy/dom/html_collection.html b/src/browser/tests/legacy/dom/html_collection.html
new file mode 100644
index 00000000..22590e58
--- /dev/null
+++ b/src/browser/tests/legacy/dom/html_collection.html
@@ -0,0 +1,67 @@
+<!DOCTYPE html>
+<body>
+  <div id="content">
+    <a id="link" href="foo" class="ok">OK</a>
+    <p id="para-empty" class="ok empty">
+      <span id="para-empty-child"></span>
+    </p>
+    <p id="para"> And</p>
+    <!--comment-->
+  </div>
+</body>
+
+<script src="../testing.js"></script>
+<script id=caseInsensitve>
+    const Ptags = document.getElementsByTagName('P');
+    testing.expectEqual(2, Ptags.length);
+    testing.expectEqual('p', Ptags.item(0).localName);
+    testing.expectEqual('p', Ptags.item(1).localName);
+</script>
+
+<script id=all>
+  let allTags = document.getElementsByTagName('*');
+  testing.expectEqual(13, allTags.length);
+  testing.expectEqual('html', allTags.item(0).localName);
+  testing.expectEqual('html', allTags.item(0).localName);
+  testing.expectEqual('head', allTags.item(1).localName);
+  testing.expectEqual('html', allTags.item(0).localName);
+  testing.expectEqual('body', allTags.item(2).localName);
+  testing.expectEqual('div', allTags.item(3).localName);
+  testing.expectEqual('p', allTags.item(7).localName);
+  testing.expectEqual('span', allTags.namedItem('para-empty-child').localName);
+
+
+  // array like
+  testing.expectEqual('html', allTags[0].localName);
+  testing.expectEqual('p', allTags[7].localName);
+  testing.expectEqual(undefined, allTags[14]);
+  testing.expectEqual('span', allTags['para-empty-child'].localName);
+  testing.expectEqual(undefined, allTags['foo']);
+</script>
+
+<script id=element>
+  let content = $('#content');
+  testing.expectEqual(4, content.getElementsByTagName('*').length);
+  testing.expectEqual(2, content.getElementsByTagName('p').length);
+  testing.expectEqual(0, content.getElementsByTagName('div').length);
+
+  testing.expectEqual(1, document.children.length);
+  testing.expectEqual(3, content.children.length);
+</script>
+
+<script id=liveness>
+  const ptags = document.getElementsByTagName('p');
+  testing.expectEqual(2, ptags.length);
+  testing.expectEqual(' And', ptags.item(1).textContent);
+
+  let p = document.createElement('p');
+  p.textContent = 'OK live';
+  // hasn't been added, still 2
+  testing.expectEqual(2, ptags.length);
+
+  testing.expectEqual(true, content.appendChild(p) != undefined);
+  testing.expectEqual(3, ptags.length);
+  testing.expectEqual('OK live', ptags.item(2).textContent);
+  testing.expectEqual(true, content.insertBefore(p, $('#para-empty')) != undefined);
+  testing.expectEqual('OK live', ptags.item(0).textContent);
+</script>
diff --git a/src/browser/tests/legacy/dom/implementation.html b/src/browser/tests/legacy/dom/implementation.html
new file mode 100644
index 00000000..81cce804
--- /dev/null
+++ b/src/browser/tests/legacy/dom/implementation.html
@@ -0,0 +1,14 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=implementation>
+  let impl = document.implementation;
+  testing.expectEqual("[object HTMLDocument]", impl.createHTMLDocument().toString());;
+
+  const doc = impl.createHTMLDocument('foo');
+  testing.expectEqual("[object HTMLDocument]", doc.toString());
+  testing.expectEqual("foo", doc.title);
+  testing.expectEqual("[object HTMLBodyElement]", doc.body.toString());
+  testing.expectEqual("[object Document]", impl.createDocument(null, 'foo').toString());
+  testing.expectEqual("[object DocumentType]", impl.createDocumentType('foo', 'bar', 'baz').toString());
+  testing.expectEqual(true, impl.hasFeature());
+</script>
diff --git a/src/browser/tests/legacy/dom/intersection_observer.html b/src/browser/tests/legacy/dom/intersection_observer.html
new file mode 100644
index 00000000..4067edba
--- /dev/null
+++ b/src/browser/tests/legacy/dom/intersection_observer.html
@@ -0,0 +1,163 @@
+<!DOCTYPE html>
+<body></body>
+<script src="../testing.js"></script>
+
+<script id=intersectionObserver>
+  {
+    // never attached
+    let count = 0;
+    const div = document.createElement('div');
+    new IntersectionObserver((entries) => {
+      count += 1;
+    }).observe(div);
+
+    testing.eventually(() => {
+      testing.expectEqual(0, count);
+    });
+  }
+
+  {
+    // not connected, but has parent
+    let count = 0;
+    const div1 = document.createElement('div');
+    const div2 = document.createElement('div');
+    new IntersectionObserver((entries) => {
+      console.log(entries[0]);
+      count += 1;
+    }).observe(div1);
+
+    div2.appendChild(div1);
+    testing.eventually(() => {
+      testing.expectEqual(1, count);
+    });
+  }
+</script>
+
+<script id=reobserve>
+  {
+    let count = 0;
+    let observer = new IntersectionObserver(entries => {
+      count += entries.length;
+    });
+
+    const div1 = document.createElement('div');
+    document.body.appendChild(div1);
+
+    // cannot fire synchronously, must be on the next tick
+    testing.expectEqual(0, count);
+    observer.observe(div1);
+    testing.expectEqual(0, count);
+    observer.observe(div1);
+    observer.observe(div1);
+    testing.expectEqual(0, count);
+
+    testing.eventually(() => {
+      testing.expectEqual(1, count);
+    });
+  }
+</script>
+
+<script id=unobserve>
+  {
+    let count = 0;
+    let observer = new IntersectionObserver(entries => {
+      count += entries.length;
+    });
+
+    const div1 = document.createElement('div');
+    document.body.appendChild(div1);
+
+    testing.expectEqual(0, count);
+    observer.observe(div1);
+    testing.expectEqual(0, count);
+    observer.observe(div1);
+    observer.observe(div1);
+    testing.expectEqual(0, count);
+
+    observer.unobserve(div1);
+    testing.eventually(() => {
+      testing.expectEqual(0, count);
+    });
+  }
+</script>
+
+<script id=disconnect>
+  {
+    let count = 0;
+    let observer = new IntersectionObserver(entries => {
+      count += entries.length;
+    });
+
+    const div1 = document.createElement('div');
+    document.body.appendChild(div1);
+
+    // cannot fire synchronously, must be on the next tick
+    testing.expectEqual(0, count);
+    observer.observe(div1);
+    testing.expectEqual(0, count);
+    observer.observe(div1);
+    observer.observe(div1);
+    testing.expectEqual(0, count);
+    observer.disconnect();
+
+    testing.eventually(() => {
+      testing.expectEqual(0, count);
+    });
+  }
+</script>
+
+<script id=entry>
+  {
+    let entry = null;
+    let observer = new IntersectionObserver(entries => {
+      entry = entries[0];
+    });
+
+    let div1 = document.createElement('div');
+    document.body.appendChild(div1);
+    new IntersectionObserver(entries => { entry = entries[0]; }).observe(div1);
+
+    testing.eventually(() => {
+      testing.expectEqual(0, entry.boundingClientRect.x);
+      testing.expectEqual(1, entry.intersectionRatio);
+      testing.expectEqual(0, entry.intersectionRect.x);
+      testing.expectEqual(0, entry.intersectionRect.y);
+      testing.expectEqual(5, entry.intersectionRect.width);
+      testing.expectEqual(5, entry.intersectionRect.height);
+      testing.expectEqual(true, entry.isIntersecting);
+      testing.expectEqual(0, entry.rootBounds.x);
+      testing.expectEqual(0, entry.rootBounds.y);
+      testing.expectEqual(5, entry.rootBounds.width);
+      testing.expectEqual(5, entry.rootBounds.height);
+      testing.expectEqual('[object HTMLDivElement]', entry.target.toString());
+    });
+  }
+</script>
+
+<script id=timing>
+  {
+    const capture = [];
+    const observer = new IntersectionObserver(() => {
+      capture.push('callback');
+    });
+
+    const div = document.createElement('div');
+    capture.push('pre-append');
+    document.body.appendChild(div);
+    capture.push('post-append');
+
+    capture.push('pre-observe');
+    observer.observe(div);
+    capture.push('post-observe');
+
+    testing.eventually(() => {
+      testing.expectEqual([
+        'pre-append',
+        'post-append',
+        'pre-observe',
+        'post-observe',
+        'callback',
+      ], capture)
+    });
+  }
+</script>
diff --git a/src/browser/tests/legacy/dom/message_channel.html b/src/browser/tests/legacy/dom/message_channel.html
new file mode 100644
index 00000000..2ab075e5
--- /dev/null
+++ b/src/browser/tests/legacy/dom/message_channel.html
@@ -0,0 +1,60 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=messageChannel>
+  const mc1 = new MessageChannel();
+  testing.expectEqual(mc1.port1, mc1.port1);
+  testing.expectEqual(mc1.port2, mc1.port2);
+  testing.expectEqual(true, mc1.port1 != mc1.port2);
+  mc1.port1.postMessage('msg1');
+
+  let message = null;
+  let target = null;
+  let currentTarget = null;
+  mc1.port2.onmessage = (e) => {
+    message = e.data;
+    target = e.target;
+    currentTarget = e.currentTarget;
+  };
+
+  //  as soon as onmessage is called, queued messages are delivered
+  testing.expectEqual('msg1', message);
+  testing.expectEqual(mc1.port2, target);
+  testing.expectEqual(mc1.port2, currentTarget);
+
+  mc1.port1.postMessage('msg2');
+  testing.expectEqual('msg2', message);
+  testing.expectEqual(mc1.port2, target);
+  testing.expectEqual(mc1.port2, currentTarget);
+
+  message = null;
+  mc1.port1.close();
+  mc1.port1.postMessage('msg3');
+  testing.expectEqual(null, message);
+
+  const mc2 = new MessageChannel();
+  mc2.port2.postMessage('msg1');
+  mc2.port1.postMessage('msg2');
+
+  let message1 = null;
+  mc2.port1.addEventListener('message', (e) => {
+    message1 = e.data;
+  });
+
+  let message2 = null;
+  mc2.port2.addEventListener('message', (e) => {
+    message2 = e.data;
+  });
+
+  testing.expectEqual(null, message1);
+  testing.expectEqual(null, message2);
+
+  mc2.port2.start();
+
+  testing.expectEqual(null, message1);
+  testing.expectEqual('msg2', message2);
+  message2 = null;
+
+  mc2.port1.start();
+  testing.expectEqual('msg1', message1);
+  testing.expectEqual(null, message2);
+</script>
diff --git a/src/browser/tests/legacy/dom/mutation_observer.html b/src/browser/tests/legacy/dom/mutation_observer.html
new file mode 100644
index 00000000..f67cb924
--- /dev/null
+++ b/src/browser/tests/legacy/dom/mutation_observer.html
@@ -0,0 +1,76 @@
+<!DOCTYPE html>
+<div></div>
+<div id=d1><p id=p1> And</p></div>
+<div id=d2><p id=p2> And</p></div>
+<div id=d3><p id=p3> And</p></div>
+
+<script src="../testing.js"></script>
+<script id=mutationObserver>
+  // doesn't crash, yay.
+  new MutationObserver(() => {}).observe(document, { childList: true });
+
+  var nb = 0;
+  var mrs;
+  let cb_this1;
+  let mu1 = new MutationObserver(function(mu) {
+     mrs = mu;
+     nb++;
+     cb_this1 = this;
+  });
+  mu1.observe(document.firstElementChild, { attributes: true, attributeOldValue: true });
+  document.firstElementChild.setAttribute("foo", "bar");
+  document.firstElementChild.firstChild.setAttribute("foo", "bar");
+
+  testing.eventually(() => {
+    testing.expectEqual(1, nb);
+    testing.expectEqual(cb_this1, mu1);
+    testing.expectEqual('attributes', mrs[0].type);
+    testing.expectEqual(document.firstElementChild, mrs[0].target);
+    testing.expectEqual('bar', mrs[0].target.getAttribute('foo'));
+    testing.expectEqual('foo', mrs[0].attributeName);
+    testing.expectEqual(null, mrs[0].oldValue);
+  });
+
+  var nb2 = 0;
+  var mrs2;
+  var node1 = $('#p1').firstChild;
+  let mu2 = new MutationObserver((mu) => {
+      mrs2 = mu;
+      nb2++;
+      cb_this2 = this;
+  })
+  mu2.observe(node1, { characterData: true, characterDataOldValue: true });
+  node1.data = "foo";
+
+  testing.eventually(() => {
+    testing.expectEqual(1, nb2);
+    testing.expectEqual(window, cb_this2);
+    testing.expectEqual('characterData', mrs2[0].type);
+    testing.expectEqual(node1, mrs2[0].target);
+    testing.expectEqual('foo', mrs2[0].target.data);
+    testing.expectEqual(' And', mrs2[0].oldValue);
+  });
+</script>
+
+<script id=callback>
+  // tests that mutation observers that have a callback which trigger the
+  // mutation observer don't crash.
+  // https://github.com/lightpanda-io/browser/issues/550
+  var node2 = $("#p2");
+  new MutationObserver(() => {
+      node2.innerText = 'a';
+  }).observe($('#d2'), { subtree:true, childList:true });
+  node2.innerText = "2";
+  testing.eventually(() => testing.expectEqual('a', node2.innerText));
+
+  var node3 = $("#p3");
+  var attrWatch = 0;
+  new MutationObserver(() => {
+      attrWatch++;
+  }).observe($('#d3'), { attributeFilter: ["name"], subtree: true });
+  node3.setAttribute("id", "1");
+
+  testing.expectEqual(0, attrWatch);
+  node3.setAttribute('name', 'other');
+  testing.eventually(() => testing.expectEqual(1, attrWatch));
+</script>
diff --git a/src/browser/tests/legacy/dom/named_node_map.html b/src/browser/tests/legacy/dom/named_node_map.html
new file mode 100644
index 00000000..7cdcf4b7
--- /dev/null
+++ b/src/browser/tests/legacy/dom/named_node_map.html
@@ -0,0 +1,19 @@
+<!DOCTYPE html>
+<div id="content"></div>
+
+<script src="../testing.js"></script>
+<script id=namedNodeMap>
+  let a = document.getElementById('content').attributes;
+  testing.expectEqual(1, a.length);
+  testing.expectEqual('[object Attr]', a.item(0).toString());
+  testing.expectEqual(null, a.item(1));
+  testing.expectEqual('[object Attr]', a.getNamedItem('id').toString());
+  testing.expectEqual(null, a.getNamedItem('foo'));
+  testing.expectEqual('[object Attr]', a.setNamedItem(a.getNamedItem('id')).toString());
+
+  testing.expectEqual('id', a['id'].name);
+  testing.expectEqual('content', a['id'].value);
+  testing.expectEqual(undefined, a['other']);
+  a[0].value = 'abc123';
+  testing.expectEqual('abc123', a[0].value);
+</script>
diff --git a/src/browser/tests/legacy/dom/node.html b/src/browser/tests/legacy/dom/node.html
new file mode 100644
index 00000000..ae9b8a3e
--- /dev/null
+++ b/src/browser/tests/legacy/dom/node.html
@@ -0,0 +1,266 @@
+<!DOCTYPE html>
+<body><div id="content">
+    <a id="link" href="foo" class="ok">OK</a>
+    <p id="para-empty" class="ok empty">
+      <span id="para-empty-child"></span>
+    </p>
+    <p id="para"> And</p>
+    <!--comment-->
+  </div>
+  <div id="rootNodeComposed"></div>
+</body>
+
+<script src="../testing.js"></script>
+<script>
+function trimAndReplace(str) {
+  str = str.replace(/(\r\n|\n|\r)/gm,'');
+  str = str.replace(/\s+/g, ' ');
+  str = str.trim();
+  return str;
+}
+
+let content = $('#content');
+let link = $('#link');
+let first_child = content.firstChild.nextSibling; // nextSibling because of line return \n
+</script>
+
+<script id=compareDocumentPosition>
+  testing.expectEqual(10, document.body.compareDocumentPosition(document.firstChild));
+  testing.expectEqual(10, $('#para-empty').compareDocumentPosition(content));
+  testing.expectEqual(20, content.compareDocumentPosition($('#para-empty')));
+  testing.expectEqual(0, link.compareDocumentPosition(link));
+  testing.expectEqual(2, $('#para-empty').compareDocumentPosition(link));
+  testing.expectEqual(4, link.compareDocumentPosition($('#para-empty')));
+</script>
+
+<script id=proto>
+  testing.expectEqual('HTMLDocument', content.getRootNode().__proto__.constructor.name);
+</script>
+
+<script id=getRootNodeComposed>
+  const testContainer = $('#rootNodeComposed');
+  const shadowHost = document.createElement('div');
+  testContainer.appendChild(shadowHost);
+  const shadowRoot = shadowHost.attachShadow({ mode: 'open' });
+  const shadowChild = document.createElement('span');
+  shadowRoot.appendChild(shadowChild);
+
+  testing.expectEqual('ShadowRoot', shadowChild.getRootNode().__proto__.constructor.name);
+  testing.expectEqual('ShadowRoot', shadowChild.getRootNode({ composed: false }).__proto__.constructor.name);
+  testing.expectEqual('HTMLDocument', shadowChild.getRootNode({ composed: true }).__proto__.constructor.name);
+  testing.expectEqual('HTMLDocument', shadowHost.getRootNode().__proto__.constructor.name);
+
+  const disconnected = document.createElement('div');
+  const disconnectedChild = document.createElement('span');
+  disconnected.appendChild(disconnectedChild);
+  testing.expectEqual('HTMLDivElement', disconnectedChild.getRootNode().__proto__.constructor.name);
+  testing.expectEqual('HTMLDivElement', disconnectedChild.getRootNode({ composed: true }).__proto__.constructor.name);
+</script>
+
+<script id=firstChild>
+  let body_first_child = document.body.firstChild;
+  testing.expectEqual('div', body_first_child.localName);
+  testing.expectEqual('HTMLDivElement', body_first_child.__proto__.constructor.name);
+  testing.expectEqual(null, $('#para-empty').firstChild.firstChild);
+</script>
+
+<script id=lastChild>
+  let last_child = content.lastChild.previousSibling; // previousSibling because of line return \n
+  testing.expectEqual('Comment', last_child.__proto__.constructor.name);
+</script>
+
+<script id=nextSibling>
+  let next_sibling = link.nextSibling.nextSibling;
+  testing.expectEqual('p', next_sibling.localName);
+  testing.expectEqual('HTMLParagraphElement', next_sibling.__proto__.constructor.name);
+  testing.expectEqual(null, $('#para-empty-child').nextSibling.nextSibling);
+</script>
+
+<script id=previousSibling>
+  let prev_sibling = $('#para-empty').previousSibling.previousSibling;
+  testing.expectEqual('a', prev_sibling.localName);
+  testing.expectEqual('HTMLAnchorElement', prev_sibling.__proto__.constructor.name);
+  testing.expectEqual(null, content.previousSibling);
+</script>
+
+<script id=parentElement>
+  let parent = $('#para').parentElement;
+  testing.expectEqual('div', parent.localName);
+  testing.expectEqual('HTMLDivElement', parent.__proto__.constructor.name)
+
+  let h = content.parentElement.parentElement;
+  testing.expectEqual(null, h.parentElement);
+  testing.expectEqual('HTMLDocument', h.parentNode.__proto__.constructor.name);
+</script>
+
+<script id=nodeName>
+  testing.expectEqual('A', first_child.nodeName);
+  testing.expectEqual('#text', link.firstChild.nodeName);
+  testing.expectEqual('#comment', last_child.nodeName);
+  testing.expectEqual('#document', document.nodeName);
+</script>
+
+<script id=nodeType>
+  testing.expectEqual(1, first_child.nodeType)
+  testing.expectEqual(3, link.firstChild.nodeType)
+  testing.expectEqual(8, last_child.nodeType)
+  testing.expectEqual(9, document.nodeType)
+</script>
+
+<script id=ownerDocument>
+  let owner = content.ownerDocument;
+  testing.expectEqual('HTMLDocument', owner.__proto__.constructor.name);
+  testing.expectEqual(null, document.ownerDocument)
+
+  let owner2 = document.createElement('div').ownerDocument;
+  testing.expectEqual('HTMLDocument', owner2.__proto__.constructor.name);
+</script>
+
+<script id=isConnected>
+  testing.expectEqual(true, content.isConnected);
+  testing.expectEqual(true, document.isConnected);
+
+  const connDiv = document.createElement('div');
+  testing.expectEqual(false, connDiv.isConnected);
+
+  const connParentDiv = document.createElement('div');
+  connParentDiv.appendChild(connDiv);
+  testing.expectEqual(false, connDiv.isConnected);
+
+  content.appendChild(connParentDiv);
+  testing.expectEqual(true, connDiv.isConnected);
+</script>
+
+<script id=nodeValue>
+  testing.expectEqual('comment', last_child.nodeValue);
+  testing.expectEqual(null, link.nodeValue);
+
+  let text = link.firstChild;
+  testing.expectEqual('OK', text.nodeValue);
+
+  text.nodeValue = 'OK modified';
+  testing.expectEqual('OK modified', text.nodeValue);
+</script>
+
+<script id=textContent>
+  testing.expectEqual('OK modified', text.textContent);
+  testing.expectEqual('OK modified And', trimAndReplace(content.textContent));
+  text.textContent = 'OK';
+  testing.expectEqual('OK', text.textContent);
+
+  testing.expectEqual('', trimAndReplace($('#para-empty').textContent));
+
+  $('#para-empty').textContent = 'OK';
+  testing.expectEqual('#text', $('#para-empty').firstChild.nodeName);
+</script>
+
+<script id=appendChild>
+  let append = document.createElement('h1');
+  testing.expectEqual('[object HTMLHeadingElement]', content.appendChild(append).toString());
+  testing.expectEqual('HTMLHeadingElement', content.lastChild.__proto__.constructor.name);
+  testing.expectEqual('[object HTMLAnchorElement]', content.appendChild(link).toString());
+</script>
+
+<script id=cloneNode>
+  let clone = link.cloneNode();
+  testing.expectEqual('[object HTMLAnchorElement]', clone.toString());
+  testing.expectEqual(null, clone.parentNode);
+  testing.expectEqual(null, clone.firstChild);
+
+  let clone_deep = link.cloneNode(true);
+  testing.expectEqual('#text', clone_deep.firstChild.nodeName);
+</script>
+
+<script id=contains>
+  testing.expectEqual(true, link.contains(text));
+  testing.expectEqual(false, text.contains(link));
+</script>
+
+<script id=hasChildNodes>
+  testing.expectEqual(true, link.hasChildNodes());
+  testing.expectEqual(false, text.hasChildNodes());
+</script>
+
+<script id=childNodesLength>
+  testing.expectEqual(1, link.childNodes.length);
+  testing.expectEqual(0, text.childNodes.length);
+</script>
+
+<script id=insertBefore>
+  let insertBefore = document.createElement('a');
+  testing.expectEqual(true, link.insertBefore(insertBefore, text) !== undefined);
+  testing.expectEqual('a', link.firstChild.localName);
+
+  let insertBefore2 = document.createElement('b');
+  testing.expectEqual('b', link.insertBefore(insertBefore2, null).localName);
+  testing.expectEqual('b', link.childNodes[link.childNodes.length - 1].localName);
+</script>
+
+<script id=isDefaultNamespace>
+  // TODO: does not seems to work
+  //   link.isDefaultNamespace('')", "true" },
+  testing.expectEqual(false, link.isDefaultNamespace('false'));
+</script>
+
+<script id=isEqualNode>
+  let equal1 = document.createElement('a');
+  let equal2 = document.createElement('a');
+  equal1.textContent = 'is equal';
+  equal2.textContent = 'is equal';
+  // TODO: does not seems to work
+  // testing.expectEqual(true, equal1.isEqualNode(equal2));
+  testing.skip();
+</script>
+
+<script id=isSameNode>
+  testing.expectEqual(true, document.body.isSameNode(document.body));
+  testing.expectEqual(false, document.body.isSameNode(content));
+</script>
+
+<script id=baseURI>
+  testing.expectEqual('http://localhost:9582/src/tests/dom/node.html', link.baseURI);
+</script>
+
+<script id=removeChild>
+  testing.expectEqual(true, content.removeChild(append) !== undefined);
+  testing.expectEqual(true, last_child.__proto__.constructor.name !== 'HTMLHeadingElement');
+</script>
+
+<script id=replaceChild>
+  let replace = document.createElement('div');
+  testing.expectEqual(true, link.replaceChild(replace, insertBefore) !== undefined);
+</script>
+
+<script id=NODE_TYPE>
+  testing.expectEqual(1, Node.ELEMENT_NODE);
+  testing.expectEqual(2, Node.ATTRIBUTE_NODE);
+  testing.expectEqual(3, Node.TEXT_NODE);
+  testing.expectEqual(4, Node.CDATA_SECTION_NODE);
+  testing.expectEqual(7, Node.PROCESSING_INSTRUCTION_NODE);
+  testing.expectEqual(8, Node.COMMENT_NODE);
+  testing.expectEqual(9, Node.DOCUMENT_NODE);
+  testing.expectEqual(10, Node.DOCUMENT_TYPE_NODE);
+  testing.expectEqual(11, Node.DOCUMENT_FRAGMENT_NODE);
+  testing.expectEqual(5, Node.ENTITY_REFERENCE_NODE);
+  testing.expectEqual(6, Node.ENTITY_NODE);
+  testing.expectEqual(12, Node.NOTATION_NODE);
+</script>
+
+<span id=token class="token" style="color:#ce9178">&quot;puppeteer &quot;</span>
+                                        <h3 id=name>Leto
+                                        <!-- -->
+                                        <!-- -->
+                                        Atreides</h3>
+<script id=normalize>
+  const token = $('#token');
+  testing.expectEqual('"puppeteer "', token.firstChild.nodeValue);
+
+  const name = $('#name');
+  testing.expectEqual([
+    "Leto\n                                        ",
+    " ",
+    "\n                                        ",
+    " ",
+    "\n                                        Atreides"
+  ], Array.from(name.childNodes).map((n) => n.nodeValue));
+</script>
diff --git a/src/browser/tests/legacy/dom/node_filter.html b/src/browser/tests/legacy/dom/node_filter.html
new file mode 100644
index 00000000..d5ac95f4
--- /dev/null
+++ b/src/browser/tests/legacy/dom/node_filter.html
@@ -0,0 +1,219 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<!-- Test fixture -->
+<div id="container">
+  <!-- comment1 -->
+  <div id="outer">
+    <!-- comment2 -->
+    <span id="inner">
+      <!-- comment3 -->
+      Text content
+      <!-- comment4 -->
+    </span>
+    <!-- comment5 -->
+  </div>
+  <!-- comment6 -->
+</div>
+
+<script id=nodeFilter>
+  testing.expectEqual(1, NodeFilter.FILTER_ACCEPT);
+  testing.expectEqual(2, NodeFilter.FILTER_REJECT);
+  testing.expectEqual(3, NodeFilter.FILTER_SKIP);
+  testing.expectEqual(4294967295, NodeFilter.SHOW_ALL);
+  testing.expectEqual(129, NodeFilter.SHOW_ELEMENT | NodeFilter.SHOW_COMMENT);
+</script>
+
+<script id=treeWalkerComments>
+  {
+    const container = $('#container');
+    const walker = document.createTreeWalker(
+      container,
+      NodeFilter.SHOW_COMMENT,
+      null,
+      false
+    );
+
+    const comments = [];
+    let node;
+    while (node = walker.nextNode()) {
+      comments.push(node.data.trim());
+    }
+
+    // Should find all 6 comments, including those nested inside elements
+    testing.expectEqual(6, comments.length);
+    testing.expectEqual('comment1', comments[0]);
+    testing.expectEqual('comment2', comments[1]);
+    testing.expectEqual('comment3', comments[2]);
+    testing.expectEqual('comment4', comments[3]);
+    testing.expectEqual('comment5', comments[4]);
+    testing.expectEqual('comment6', comments[5]);
+  }
+</script>
+
+<script id=treeWalkerElements>
+  {
+    const container = $('#container');
+    const walker = document.createTreeWalker(
+      container,
+      NodeFilter.SHOW_ELEMENT,
+      null,
+      false
+    );
+
+    const elements = [];
+    let node;
+    while (node = walker.nextNode()) {
+      if (node.id) {
+        elements.push(node.id);
+      }
+    }
+
+    // Should find the 2 nested elements (outer and inner)
+    testing.expectEqual(2, elements.length);
+    testing.expectEqual('outer', elements[0]);
+    testing.expectEqual('inner', elements[1]);
+  }
+</script>
+
+<script id=treeWalkerAll>
+  {
+    const container = $('#container');
+    const walker = document.createTreeWalker(
+      container,
+      NodeFilter.SHOW_ALL,
+      null,
+      false
+    );
+
+    let commentCount = 0;
+    let elementCount = 0;
+    let textCount = 0;
+
+    let node;
+    while (node = walker.nextNode()) {
+      if (node.nodeType === 8) commentCount++;      // Comment
+      else if (node.nodeType === 1) elementCount++;  // Element
+      else if (node.nodeType === 3) textCount++;     // Text
+    }
+
+    testing.expectEqual(6, commentCount);
+    testing.expectEqual(2, elementCount);
+    testing.expectEqual(true, textCount > 0);
+  }
+</script>
+
+<script id=treeWalkerCombined>
+  {
+    const container = $('#container');
+    const walker = document.createTreeWalker(
+      container,
+      NodeFilter.SHOW_ELEMENT | NodeFilter.SHOW_COMMENT,
+      null,
+      false
+    );
+
+    let commentCount = 0;
+    let elementCount = 0;
+
+    let node;
+    while (node = walker.nextNode()) {
+      if (node.nodeType === 8) commentCount++;      // Comment
+      else if (node.nodeType === 1) elementCount++;  // Element
+    }
+
+    // Should find 6 comments and 2 elements, but no text nodes
+    testing.expectEqual(6, commentCount);
+    testing.expectEqual(2, elementCount);
+  }
+</script>
+
+<script id=treeWalkerCustomFilter>
+  {
+    const container = $('#container');
+
+    // Filter that accepts only elements with id
+    const walker = document.createTreeWalker(
+      container,
+      NodeFilter.SHOW_ELEMENT,
+      {
+        acceptNode: function(node) {
+          return node.id ? NodeFilter.FILTER_ACCEPT : NodeFilter.FILTER_SKIP;
+        }
+      },
+      false
+    );
+
+    const elements = [];
+    let node;
+    while (node = walker.nextNode()) {
+      elements.push(node.id);
+    }
+
+    // Should find only elements with id (outer and inner)
+    testing.expectEqual(2, elements.length);
+    testing.expectEqual('outer', elements[0]);
+    testing.expectEqual('inner', elements[1]);
+  }
+</script>
+
+<script id=nodeIteratorComments>
+  {
+    const container = $('#container');
+    const iterator = document.createNodeIterator(
+      container,
+      NodeFilter.SHOW_COMMENT,
+      null,
+      false
+    );
+
+    const comments = [];
+    let node;
+    while (node = iterator.nextNode()) {
+      comments.push(node.data.trim());
+    }
+
+    // Should find all 6 comments, including those nested inside elements
+    testing.expectEqual(6, comments.length);
+    testing.expectEqual('comment1', comments[0]);
+    testing.expectEqual('comment2', comments[1]);
+    testing.expectEqual('comment3', comments[2]);
+    testing.expectEqual('comment4', comments[3]);
+    testing.expectEqual('comment5', comments[4]);
+    testing.expectEqual('comment6', comments[5]);
+  }
+</script>
+
+<script id=reactLikeScenario>
+  {
+    // Test a React-like scenario with comment markers
+    const div = document.createElement('div');
+    div.innerHTML = `
+      <a href="/">
+        <!--$-->
+        <svg viewBox="0 0 10 10">
+          <path d="M0,0 L10,10" />
+        </svg>
+        <!--/$-->
+      </a>
+    `;
+
+    const walker = document.createTreeWalker(
+      div,
+      NodeFilter.SHOW_COMMENT,
+      null,
+      false
+    );
+
+    const comments = [];
+    let node;
+    while (node = walker.nextNode()) {
+      comments.push(node.data);
+    }
+
+    // Should find both React markers even though they're nested inside <a>
+    testing.expectEqual(2, comments.length);
+    testing.expectEqual('$', comments[0]);
+    testing.expectEqual('/$', comments[1]);
+  }
+</script>
diff --git a/src/browser/tests/legacy/dom/node_iterator.html b/src/browser/tests/legacy/dom/node_iterator.html
new file mode 100644
index 00000000..6225dea4
--- /dev/null
+++ b/src/browser/tests/legacy/dom/node_iterator.html
@@ -0,0 +1,62 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=nodeIterator>
+  const nodeIterator = document.createNodeIterator(
+    document.body,
+    NodeFilter.SHOW_ELEMENT,
+    {
+      acceptNode(node) {
+        return NodeFilter.FILTER_ACCEPT;
+      },
+    },
+  );
+  testing.expectEqual('BODY', nodeIterator.nextNode().nodeName);
+
+  testing.expectEqual('DIV', nodeIterator.nextNode().nodeName);
+  testing.expectEqual('A', nodeIterator.nextNode().nodeName);
+  testing.expectEqual('A', nodeIterator.previousNode().nodeName); // pointer_before_current flips
+  testing.expectEqual('A', nodeIterator.nextNode().nodeName); // pointer_before_current flips
+  testing.expectEqual('A', nodeIterator.previousNode().nodeName); // pointer_before_current flips
+  testing.expectEqual('DIV', nodeIterator.previousNode().nodeName);
+  testing.expectEqual('BODY', nodeIterator.previousNode().nodeName);
+  testing.expectEqual(null, nodeIterator.previousNode()); // Not HEAD since body is root
+  testing.expectEqual(null, nodeIterator.previousNode()); // Keeps returning null
+  testing.expectEqual('BODY', nodeIterator.nextNode().nodeName);
+
+  nodeIterator.nextNode();
+  nodeIterator.nextNode();
+  nodeIterator.nextNode();
+  testing.expectEqual('SPAN', nodeIterator.nextNode().nodeName);
+  testing.expectEqual('P', nodeIterator.nextNode().nodeName);
+  testing.expectEqual(null, nodeIterator.nextNode()); // Just the last one
+  testing.expectEqual(null ,nodeIterator.nextNode()); // Keeps returning null
+  testing.expectEqual('P', nodeIterator.previousNode().nodeName);
+
+  const notationIterator = document.createNodeIterator(
+    document.body,
+    NodeFilter.SHOW_NOTATION,
+  );
+  testing.expectEqual(null, notationIterator.nextNode());
+  testing.expectEqual(null, notationIterator.previousNode());
+
+  testing.expectEqual(1, nodeIterator.filter.acceptNode(document.body));
+  testing.expectEqual(null, notationIterator.filter);
+
+  const rejectIterator = document.createNodeIterator(
+    document.body,
+    NodeFilter.SHOW_ALL,
+    (e => { return NodeFilter.FILTER_REJECT}),
+  );
+  testing.expectEqual(2, rejectIterator.filter(document.body));
+</script>
+
+<body>
+    <div id="content">
+    <a id="link" href="foo" class="ok">OK</a>
+    <p id="para-empty" class="ok empty">
+      <span id="para-empty-child"></span>
+    </p>
+    <p id="para"> And</p>
+    <!--comment-->
+  </div>
+</body>
diff --git a/src/browser/tests/legacy/dom/node_list.html b/src/browser/tests/legacy/dom/node_list.html
new file mode 100644
index 00000000..911b8aa8
--- /dev/null
+++ b/src/browser/tests/legacy/dom/node_list.html
@@ -0,0 +1,19 @@
+<!DOCTYPE html>
+<div id="content">
+  <a id="link" href="foo" class="ok">OK</a>
+  <p id="para-empty" class="ok empty">
+    <span id="para-empty-child"></span>
+  </p>
+  <p id="para"> And</p>
+  <!--comment-->
+</div>
+
+<script src="../testing.js"></script>
+<script id=nodeList>
+  let list = document.getElementById('content').childNodes;
+  testing.expectEqual(9, list.length);
+  testing.expectEqual('Text', list[0].__proto__.constructor.name);
+  let i = 0;
+  list.forEach(function (n, idx) { i += idx; });
+  testing.expectEqual(36, i);
+</script>
diff --git a/src/browser/tests/legacy/dom/node_owner.html b/src/browser/tests/legacy/dom/node_owner.html
new file mode 100644
index 00000000..0aec74c5
--- /dev/null
+++ b/src/browser/tests/legacy/dom/node_owner.html
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<div id="target-container">
+  <p id="reference-node">
+  I am the original reference node.
+  </p>
+</div>
+
+<script src="../testing.js"></script>
+<script id=nodeOwner>
+  const parser = new DOMParser();
+  const newDoc = parser.parseFromString('<div id="new-node"><p>Hey</p><span>Marked</span></div>', 'text/html');
+  const newNode = newDoc.getElementById('new-node');
+  const parent = $('#target-container');
+  const referenceNode = $('#reference-node');
+
+  parent.insertBefore(newNode, referenceNode);
+  const k = $('#new-node');
+  const ptag = k.querySelector('p');
+  const spanTag = k.querySelector('span');
+  const anotherDoc = parser.parseFromString('<div id="another-new-node"></div>', 'text/html');
+  const anotherNewNode = anotherDoc.getElementById('another-new-node');
+  testing.expectEqual('[object HTMLDivElement]', parent.appendChild(anotherNewNode).toString());
+
+
+  testing.expectEqual(newNode.ownerDocument, parent.ownerDocument);
+  testing.expectEqual(anotherNewNode.ownerDocument, parent.ownerDocument);
+  testing.expectEqual('P', newNode.firstChild.nodeName);
+  testing.expectEqual(parent.ownerDocument, ptag.ownerDocument);
+  testing.expectEqual(parent.ownerDocument, spanTag.ownerDocument);
+  testing.expectEqual(true, parent.contains(newNode));
+  testing.expectEqual(true, parent.contains(anotherNewNode));
+  testing.expectEqual(false, anotherDoc.contains(anotherNewNode));
+  testing.expectEqual(false, newDoc.contains(newNode));
+</script>
diff --git a/src/browser/tests/legacy/dom/performance.html b/src/browser/tests/legacy/dom/performance.html
new file mode 100644
index 00000000..0fbfe6fd
--- /dev/null
+++ b/src/browser/tests/legacy/dom/performance.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=performance>
+  let performance = window.performance;
+  testing.expectEqual(true, performance instanceof Performance);
+
+  let mark1 = performance.mark("start");
+  testing.expectEqual(true, mark1 instanceof PerformanceMark);
+  testing.expectEqual('start', mark1.name);
+  testing.expectEqual('mark', mark1.entryType);
+  testing.expectEqual(0, mark1.duration);
+  testing.expectEqual(null, mark1.detail);
+
+  let mark2 = performance.mark("start", {startTime: 32939393.9});
+  testing.expectEqual(32939393.9, mark2.startTime);
+</script>
diff --git a/src/browser/tests/legacy/dom/performance_observer.html b/src/browser/tests/legacy/dom/performance_observer.html
new file mode 100644
index 00000000..303fc15f
--- /dev/null
+++ b/src/browser/tests/legacy/dom/performance_observer.html
@@ -0,0 +1,5 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=performanceObserver>
+  testing.expectEqual(0, PerformanceObserver.supportedEntryTypes.length);
+</script>
diff --git a/src/browser/tests/legacy/dom/processing_instruction.html b/src/browser/tests/legacy/dom/processing_instruction.html
new file mode 100644
index 00000000..67bc8fc4
--- /dev/null
+++ b/src/browser/tests/legacy/dom/processing_instruction.html
@@ -0,0 +1,22 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=processingInstruction>
+  let pi = document.createProcessingInstruction('foo', 'bar');
+  testing.expectEqual('foo', pi.target);
+  testing.expectEqual('bar', pi.data);
+  pi.data = 'foo';
+  testing.expectEqual('foo', pi.data);
+
+  let pi2 = pi.cloneNode();
+  testing.expectEqual(7, pi2.nodeType);
+
+  let pi11 = document.createProcessingInstruction('target1', 'data1');
+  let pi12 = document.createProcessingInstruction('target2', 'data2');
+  let pi13 = document.createProcessingInstruction('target1', 'data1');
+  testing.expectEqual(true, pi11.isEqualNode(pi11));
+  testing.expectEqual(true, pi11.isEqualNode(pi13));
+  testing.expectEqual(false, pi11.isEqualNode(pi12));
+  testing.expectEqual(false, pi12.isEqualNode(pi13));
+  testing.expectEqual(false, pi11.isEqualNode(document));
+  testing.expectEqual(false, document.isEqualNode(pi11));
+</script>
diff --git a/src/browser/tests/legacy/dom/range.html b/src/browser/tests/legacy/dom/range.html
new file mode 100644
index 00000000..a60862ca
--- /dev/null
+++ b/src/browser/tests/legacy/dom/range.html
@@ -0,0 +1,41 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<div id=content><!-- hello world --><p>over 9000</p></div>
+
+<script id="constructor">
+  let range = new Range();
+  testing.expectEqual(true, range instanceof Range);
+  testing.expectEqual(true, range instanceof AbstractRange);
+
+// Test initial state - collapsed range
+  testing.expectEqual(true, range.collapsed);
+  testing.expectEqual(0, range.startOffset);
+  testing.expectEqual(0, range.endOffset);
+  testing.expectEqual(true, range.startContainer instanceof HTMLDocument);
+  testing.expectEqual(true, range.endContainer instanceof HTMLDocument);
+</script>
+
+<script id="createRange">
+  let docRange = document.createRange();
+  testing.expectEqual(true, docRange instanceof Range);
+  testing.expectEqual(true, docRange.collapsed);
+</script>
+
+<script id=textRange>
+  const container = $('#content');
+  const commentNode = container.childNodes[0];
+  testing.expectEqual(' hello world ', commentNode.nodeValue);
+
+  const textRange = document.createRange();
+  textRange.selectNodeContents(commentNode);
+  testing.expectEqual(0, textRange.startOffset);
+  testing.expectEqual(13, textRange.endOffset); // length of comment
+</script>
+
+<script id=nodeRange>
+  const nodeRange = document.createRange();
+  nodeRange.selectNodeContents(container);
+  testing.expectEqual(0, nodeRange.startOffset);
+  testing.expectEqual(2, nodeRange.endOffset); // length of container.childNodes
+</script>
diff --git a/src/browser/tests/legacy/dom/shadow_root.html b/src/browser/tests/legacy/dom/shadow_root.html
new file mode 100644
index 00000000..88a302db
--- /dev/null
+++ b/src/browser/tests/legacy/dom/shadow_root.html
@@ -0,0 +1,49 @@
+<!DOCTYPE html>
+<div id=conflict>node</div>
+
+<script src="../testing.js"></script>
+<script id=shadow_root>
+  const div1 = document.createElement('div');
+  let sr1 = div1.attachShadow({mode: 'open'});
+  testing.expectEqual(div1, sr1.host);
+  testing.expectEqual(sr1, div1.attachShadow({mode: 'open'}));
+  testing.expectEqual(sr1, div1.shadowRoot);
+
+  testing.expectError('Error: NotSupportedError', () => {
+    div1.attachShadow({mode: 'closed'});
+  });
+
+  sr1.append(document.createElement('div'));
+  sr1.append(document.createElement('span'));
+  testing.expectEqual(2, sr1.childElementCount);
+
+  // re-attaching clears it
+  testing.expectEqual(sr1, div1.attachShadow({mode: 'open'}));
+  testing.expectEqual(0, sr1.childElementCount);
+
+
+  const div2 = document.createElement('di2');
+  let sr2 = div2.attachShadow({mode: 'closed'});
+  testing.expectEqual(div2, sr2.host);
+  testing.expectEqual(null, div2.shadowRoot) // null when attached with 'closed'
+
+
+  testing.expectEqual(null, sr2.getElementById('conflict'));
+  const n1 = document.createElement('div');
+  n1.id = 'conflict';
+  sr2.append(n1);
+  testing.expectEqual(n1, sr2.getElementById('conflict'));
+
+  const acss = sr2.adoptedStyleSheets;
+  testing.expectEqual(0, acss.length);
+  acss.push(new CSSStyleSheet());
+  testing.expectEqual(1, acss.length);
+
+  sr1.innerHTML = '<p>hello</p>';
+  testing.expectEqual('<p>hello</p>', sr1.innerHTML);
+  testing.expectEqual('[object HTMLParagraphElement]', sr1.querySelector('*').toString());
+
+  sr1.innerHTML = null;
+  testing.expectEqual('', sr1.innerHTML);
+  testing.expectEqual(null, sr1.querySelector('*'));
+  </script>
diff --git a/src/browser/tests/legacy/dom/text.html b/src/browser/tests/legacy/dom/text.html
new file mode 100644
index 00000000..d7ceba08
--- /dev/null
+++ b/src/browser/tests/legacy/dom/text.html
@@ -0,0 +1,19 @@
+<!DOCTYPE html>
+<a id="link" href="foo" class="ok">OK</a>
+
+<script src="../testing.js"></script>
+<script id=text>
+  let t = new Text('foo');
+  testing.expectEqual('foo', t.data);
+
+  let emptyt = new Text();
+  testing.expectEqual('', emptyt.data);
+
+  let text = $('#link').firstChild;
+  testing.expectEqual('OK', text.wholeText);
+
+  text.data = 'OK modified';
+  let split = text.splitText('OK'.length);
+  testing.expectEqual(' modified', split.data);
+  testing.expectEqual('OK', text.data);
+</script>
diff --git a/src/browser/tests/legacy/dom/token_list.html b/src/browser/tests/legacy/dom/token_list.html
new file mode 100644
index 00000000..b04d5658
--- /dev/null
+++ b/src/browser/tests/legacy/dom/token_list.html
@@ -0,0 +1,64 @@
+<!DOCTYPE html>
+<p id="para-empty" class="ok empty">
+
+<script src="../testing.js"></script>
+<script id=tokenList>
+  let gs = $('#para-empty');
+
+  let cl = gs.classList;
+  testing.expectEqual('ok empty', gs.className);
+  testing.expectEqual('ok empty', cl.value);
+  testing.expectEqual(2, cl.length);
+
+  gs.className = 'foo bar baz';
+  testing.expectEqual('foo bar baz', gs.className);
+  testing.expectEqual(3, cl.length);
+
+  gs.className = 'ok empty';
+  testing.expectEqual(2, cl.length);
+
+  let cl2 = gs.classList;
+  testing.expectEqual(2, cl2.length);
+  testing.expectEqual('ok', cl2.item(0));
+  testing.expectEqual('empty', cl2.item(1));
+  testing.expectEqual(true, cl2.contains('ok'));
+  testing.expectEqual(false, cl2.contains('nok'));
+
+  cl2.add('foo', 'bar', 'baz');
+  testing.expectEqual(5, cl2.length);
+
+  cl2.remove('foo', 'bar', 'baz');
+  testing.expectEqual(2, cl2.length);
+
+  let cl3 = gs.classList;
+  testing.expectEqual(false, cl3.toggle('ok'));
+  testing.expectEqual(true, cl3.toggle('ok'));
+  testing.expectEqual(2, cl3.length);
+
+  let cl4 = gs.classList;
+  testing.expectEqual(true, cl4.replace('ok', 'nok'));
+  testing.expectEqual("empty nok", cl4.value);
+  testing.expectEqual(true, cl4.replace('nok', 'ok'));
+  testing.expectEqual("empty ok", cl4.value);
+
+  let cl5 = gs.classList;
+  let keys = [...cl5.keys()];
+  testing.expectEqual(2, keys.length);
+  testing.expectEqual(0, keys[0]);
+  testing.expectEqual(1, keys[1]);
+
+  let values = [...cl5.values()];
+  testing.expectEqual(2, values.length);
+  testing.expectEqual('empty', values[0]);
+  testing.expectEqual('ok', values[1]);
+
+  let entries = [...cl5.entries()];
+  testing.expectEqual(2, entries.length);
+  testing.expectEqual([0, 'empty'], entries[0]);
+  testing.expectEqual([1, 'ok'], entries[1]);
+
+  let cl6 = gs.classList;
+  cl6.value = 'a  b  ccc';
+  testing.expectEqual('a  b  ccc', cl6.value);
+  testing.expectEqual('a  b  ccc', cl6.toString());
+</script>
diff --git a/src/browser/tests/legacy/encoding/decoder.html b/src/browser/tests/legacy/encoding/decoder.html
new file mode 100644
index 00000000..8a93dc46
--- /dev/null
+++ b/src/browser/tests/legacy/encoding/decoder.html
@@ -0,0 +1,60 @@
+<!DOCTYPE html>
+<meta charset="UTF-8">
+
+<script src="../testing.js"></script>
+<script id=decoder>
+  let d1 = new TextDecoder();
+  testing.expectEqual('utf-8', d1.encoding);
+  testing.expectEqual(false, d1.fatal);
+  testing.expectEqual(false, d1.ignoreBOM);
+
+  testing.expectEqual('', d1.decode());
+  testing.expectEqual('𠮷', d1.decode(new Uint8Array([240, 160, 174, 183])));
+  testing.expectEqual('𠮷', d1.decode(new Uint8Array([0xEF, 0xBB, 0xBF, 240, 160, 174, 183])));
+  testing.expectEqual('�2', d1.decode(new Uint8Array([249, 50])));
+
+  {
+    const buffer = new ArrayBuffer(4);
+    const ints = new Uint8Array(buffer)
+    ints[0] = 240;
+    ints[1] = 160;
+    ints[2] = 174;
+    ints[3] = 183;
+    testing.expectEqual('𠮷', d1.decode(buffer));
+  }
+
+  {
+    const buffer = new ArrayBuffer(4);
+    const dv = new DataView(buffer);
+    dv.setUint8(0, 240);
+    dv.setUint8(1, 160);
+    dv.setUint8(2, 174);
+    dv.setUint8(3, 183);
+    testing.expectEqual('𠮷', d1.decode(dv));
+  }
+
+  let d2 = new TextDecoder('utf8', {fatal: true})
+  testing.expectError('Error: InvalidUtf8', () => {
+    let data  = new Uint8Array([240, 240, 160, 174, 183]);
+    d2.decode(data);
+  });
+</script>
+
+<script id=stream>
+  let d3 = new TextDecoder();
+  testing.expectEqual('', d2.decode(new Uint8Array([226, 153]), { stream: true }));
+  testing.expectEqual('♥', d2.decode(new Uint8Array([165]), { stream: true }));
+</script>
+
+<script id=slice>
+    const buf1 = new ArrayBuffer(7);
+    const arr1 = new Uint8Array(buf1)
+    arr1[0] = 80;
+    arr1[1] = 81;
+    arr1[2] = 82;
+    arr1[3] = 83;
+    arr1[4] = 84;
+    arr1[5] = 85;
+    arr1[6] = 86;
+    testing.expectEqual('RST', d3.decode(new Uint8Array(buf1, 2, 3)));
+</script>
diff --git a/src/browser/tests/legacy/encoding/encoder.html b/src/browser/tests/legacy/encoding/encoder.html
new file mode 100644
index 00000000..affcd575
--- /dev/null
+++ b/src/browser/tests/legacy/encoding/encoder.html
@@ -0,0 +1,14 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=encoder>
+  var encoder = new TextEncoder();
+  testing.expectEqual('utf-8', encoder.encoding);
+  testing.expectEqual([226, 130, 172], Array.from(encoder.encode('€')));
+
+  // Invalid utf-8 sequence.
+  // Browsers give a different result for this, they decode it to:
+  //    50, 50, 54, 44, 52, 48, 44, 49, 54, 49
+  testing.expectError('Error: InvalidUtf8', () => {
+    encoder.encode(new Uint8Array([0xE2,0x28,0xA1]));
+  });
+</script>
diff --git a/src/browser/tests/legacy/events/composition.html b/src/browser/tests/legacy/events/composition.html
new file mode 100644
index 00000000..b5a6a710
--- /dev/null
+++ b/src/browser/tests/legacy/events/composition.html
@@ -0,0 +1,36 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=noNata>
+  {
+    let event = new CompositionEvent("test", {});
+    testing.expectEqual(true, event instanceof CompositionEvent);
+    testing.expectEqual(true, event instanceof Event);
+
+    testing.expectEqual("test", event.type);
+    testing.expectEqual("", event.data);
+  }
+</script>
+
+<script id=withData>
+  {
+    let event = new CompositionEvent("test2", {data: "over 9000!"});
+    testing.expectEqual("test2", event.type);
+    testing.expectEqual("over 9000!", event.data);
+  }
+</script>
+
+<script id=dispatch>
+  {
+    let called = 0;
+    document.addEventListener('CE', (e) => {
+      testing.expectEqual('test-data', e.data);
+      testing.expectEqual(true, e instanceof CompositionEvent);
+      called += 1
+    });
+
+    document.dispatchEvent(new CompositionEvent('CE', {data: 'test-data'}));
+    testing.expectEqual(1, called);
+  }
+</script>
+
diff --git a/src/browser/tests/legacy/events/custom.html b/src/browser/tests/legacy/events/custom.html
new file mode 100644
index 00000000..cb6ddd2b
--- /dev/null
+++ b/src/browser/tests/legacy/events/custom.html
@@ -0,0 +1,25 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=custom>
+  let capture = null;
+  const el = document.createElement('div');
+  el.addEventListener('c1', (e) => { capture = 'c1-' + new String(e.detail)});
+  el.addEventListener('c2', (e) => { capture = 'c2-' + new String(e.detail.over)});
+
+  el.dispatchEvent(new CustomEvent('c1'));
+  testing.expectEqual("c1-null", capture);
+
+  el.dispatchEvent(new CustomEvent('c1', {detail: '123'}));
+  testing.expectEqual("c1-123", capture);
+
+  el.dispatchEvent(new CustomEvent('c2', {detail: {over: 9000}}));
+  testing.expectEqual("c2-9000", capture);
+
+  let window_calls = 0;
+  window.addEventListener('c1', () => {
+    window_calls += 1;
+  });
+
+  el.dispatchEvent(new CustomEvent('c1', {bubbles: true}));
+  testing.expectEqual(1, window_calls);
+</script>
diff --git a/src/browser/tests/legacy/events/event.html b/src/browser/tests/legacy/events/event.html
new file mode 100644
index 00000000..752d64ba
--- /dev/null
+++ b/src/browser/tests/legacy/events/event.html
@@ -0,0 +1,139 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<div id=content>
+  <p id="para"></p>
+</div>
+
+<script id=dispatch>
+  const startTime =  new Event('x').timeStamp;
+
+  let content = $('#content');
+  // let para = document.getElementById('para');
+  var nb = 0;
+  var evt = null;
+
+  const incrementCallback = function(e) {
+    evt = e;
+    nb += 1;
+    e.preventDefault();
+  }
+
+  content.addEventListener('dispatch', incrementCallback);
+
+  content.dispatchEvent(new Event('dispatch', {bubbles: true, cancelable: true}));
+  testing.expectEqual(1, nb);
+  testing.expectEqual(content, evt.target);
+  testing.expectEqual(true, evt.bubbles);
+  testing.expectEqual(true, evt.cancelable);
+  testing.expectEqual(true, evt.defaultPrevented);
+  testing.expectEqual(true, evt.isTrusted);
+  testing.expectEqual(true, evt.timeStamp >= Math.floor(startTime));
+</script>
+
+<script id=propogate>
+  nb = 0;
+  let para = $('#para');
+  // the stop listener is capturing, so it propogates down
+  content.addEventListener('stop',function(e) {
+    e.stopPropagation();
+    nb += 1;
+   }, true)
+
+  para.addEventListener('stop',function(e) {
+    nb += 10;
+  });
+
+  para.dispatchEvent(new Event('stop'));
+  // didn't propogate down (because of capturing) to para handler
+  testing.expectEqual(1, nb);
+</script>
+
+<script id=immediate>
+  nb = 0;
+
+  content.addEventListener('immediate', function(e) {
+    e.stopImmediatePropagation();
+    nb += 1;
+  });
+
+  // the following event listener will not be invoked
+  content.addEventListener('immediate', function(e) {
+    nb += 10;
+  });
+
+  content.dispatchEvent(new Event('immediate'));
+  testing.expectEqual(1, nb);
+</script>
+
+<script id=legacy>
+  nb = 0;
+  content.addEventListener('legacy', incrementCallback);
+  let evtLegacy = document.createEvent('Event');
+  evtLegacy.initEvent('legacy');
+  content.dispatchEvent(evtLegacy);
+  testing.expectEqual(1, nb);
+</script>
+
+<script id=removeListener>
+  nb = 0;
+  document.addEventListener('count', incrementCallback);
+  document.removeEventListener('count', incrementCallback);
+  document.dispatchEvent(new Event('count'));
+  testing.expectEqual(0, nb);
+</script>
+
+<script id=once>
+  document.addEventListener('count', incrementCallback, {once: true});
+  document.dispatchEvent(new Event('count'));
+  document.dispatchEvent(new Event('count'));
+  document.dispatchEvent(new Event('count'));
+  testing.expectEqual(1, nb);
+</script>
+
+<script id=abortController>
+  nb = 0;
+
+  let ac = new AbortController()
+  document.addEventListener('count', incrementCallback, {signal: ac.signal})
+  document.dispatchEvent(new Event('count'));
+  document.dispatchEvent(new Event('count'));
+  ac.abort();
+  document.dispatchEvent(new Event('count'));
+  testing.expectEqual(2, nb);
+  document.removeEventListener('count', incrementCallback);
+</script>
+
+<script id=composedPath>
+  testing.expectEqual([], new Event('').composedPath());
+
+  let div1 = document.createElement('div');
+  let sr1 = div1.attachShadow({mode: 'open'});
+  sr1.innerHTML = "<p id=srp1></p>";
+  document.getElementsByTagName('body')[0].appendChild(div1);
+
+  let cp = null;
+  const shadowCallback = function(e) {
+    cp = e.composedPath().map((n) => n.id || n.nodeName || n.toString());
+  }
+
+  div1.addEventListener('click', shadowCallback);
+  sr1.getElementById('srp1').click();
+  testing.expectEqual(
+    ['srp1', '#document-fragment', 'DIV', 'BODY', 'HTML', '#document', '[object Window]'],
+    cp
+  );
+
+  let div2 = document.createElement('div');
+  let sr2 = div2.attachShadow({mode: 'closed'});
+  sr2.innerHTML = "<p id=srp2></p>";
+  document.getElementsByTagName('body')[0].appendChild(div2);
+
+  cp = null;
+  div2.addEventListener('click', shadowCallback);
+  sr2.getElementById('srp2').click();
+  testing.expectEqual(
+    ['DIV', 'BODY', 'HTML', '#document', '[object Window]'],
+    cp
+  );
+</script>
diff --git a/src/browser/tests/legacy/events/keyboard.html b/src/browser/tests/legacy/events/keyboard.html
new file mode 100644
index 00000000..2b3dbefb
--- /dev/null
+++ b/src/browser/tests/legacy/events/keyboard.html
@@ -0,0 +1,88 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=default>
+  let event = new KeyboardEvent("test", { key: "a" });
+  testing.expectEqual(true, event instanceof KeyboardEvent);
+  testing.expectEqual(true, event instanceof Event);
+
+  testing.expectEqual("test", event.type);
+  testing.expectEqual("a", event.key);
+
+  testing.expectEqual(0, event.location);
+  testing.expectEqual(false, event.repeat);
+  testing.expectEqual(false, event.isComposing);
+
+  testing.expectEqual(false, event.ctrlKey);
+  testing.expectEqual(false, event.shiftKey);
+  testing.expectEqual(false, event.metaKey);
+  testing.expectEqual(false, event.altKey);
+</script>
+
+<script id=getModifierState>
+  event = new KeyboardEvent("test", {
+    altKey: true,
+    shiftKey: true,
+    metaKey: true,
+    ctrlKey: true,
+  });
+
+  testing.expectEqual(true, event.getModifierState("Alt"));
+  testing.expectEqual(true, event.getModifierState("AltGraph"));
+  testing.expectEqual(true, event.getModifierState("Control"));
+  testing.expectEqual(true, event.getModifierState("Shift"));
+  testing.expectEqual(true, event.getModifierState("Meta"));
+  testing.expectEqual(true, event.getModifierState("OS"));
+  testing.expectEqual(true, event.getModifierState("Accel"));
+</script>
+
+<script id=keyDownListener>
+  event = new KeyboardEvent("keydown", { key: "z" });
+  let isKeyDown = false;
+
+  document.addEventListener("keydown", (e) => {
+    isKeyDown = true;
+
+    testing.expectEqual(true, e instanceof KeyboardEvent);
+    testing.expectEqual(true, e instanceof Event);
+    testing.expectEqual("z", event.key);
+  });
+
+  document.dispatchEvent(event);
+
+  testing.expectEqual(true, isKeyDown);
+</script>
+
+<script id=keyUpListener>
+  event = new KeyboardEvent("keyup", { key: "x" });
+  let isKeyUp = false;
+
+  document.addEventListener("keyup", (e) => {
+    isKeyUp = true;
+
+    testing.expectEqual(true, e instanceof KeyboardEvent);
+    testing.expectEqual(true, e instanceof Event);
+    testing.expectEqual("x", event.key);
+  });
+
+  document.dispatchEvent(event);
+
+  testing.expectEqual(true, isKeyUp);
+</script>
+
+<script id=keyPressListener>
+  event = new KeyboardEvent("keypress", { key: "w" });
+  let isKeyPress = false;
+
+  document.addEventListener("keypress", (e) => {
+    isKeyPress = true;
+
+    testing.expectEqual(true, e instanceof KeyboardEvent);
+    testing.expectEqual(true, e instanceof Event);
+    testing.expectEqual("w", event.key);
+  });
+
+  document.dispatchEvent(event);
+
+  testing.expectEqual(true, isKeyPress);
+</script>
diff --git a/src/browser/tests/legacy/events/mouse.html b/src/browser/tests/legacy/events/mouse.html
new file mode 100644
index 00000000..4c9b3f63
--- /dev/null
+++ b/src/browser/tests/legacy/events/mouse.html
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=default>
+  let event = new MouseEvent('click');
+  testing.expectEqual('click', event.type);
+  testing.expectEqual(true, event instanceof MouseEvent);
+  testing.expectEqual(true, event instanceof Event);
+  testing.expectEqual(0, event.clientX);
+  testing.expectEqual(0, event.clientY);
+  testing.expectEqual(0, event.screenX);
+  testing.expectEqual(0, event.screenY);
+</script>
+
+<script id=parameters>
+  let new_event = new MouseEvent('click', { 'button': 0, 'clientX': 10, 'clientY': 20 });
+  testing.expectEqual(0, new_event.button);
+  testing.expectEqual(10, new_event.x);
+  testing.expectEqual(20, new_event.y);
+  testing.expectEqual(10, new_event.screenX);
+  testing.expectEqual(20, new_event.screenY);
+</script>
+
+<script id=listener>
+  let me = new MouseEvent('click');
+  testing.expectEqual(true, me instanceof Event);
+
+  var evt = null;
+  document.addEventListener('click', function (e) {
+    evt = e;
+  });
+  document.dispatchEvent(me);
+  testing.expectEqual('click', evt.type);
+  testing.expectEqual(true, evt instanceof MouseEvent);
+</script>
diff --git a/src/browser/tests/legacy/fetch/fetch.html b/src/browser/tests/legacy/fetch/fetch.html
new file mode 100644
index 00000000..877f887b
--- /dev/null
+++ b/src/browser/tests/legacy/fetch/fetch.html
@@ -0,0 +1,34 @@
+<script src="../testing.js"></script>
+<script id=fetch type=module>
+  const promise1 = new Promise((resolve) => {
+    fetch('http://127.0.0.1:9582/xhr/json')
+    .then((res) => {
+      testing.expectEqual('cors', res.type);
+      return res.json()
+    })
+    .then((json) => {
+      resolve(json);
+    });
+  });
+
+  testing.async(promise1, (json) => {
+    testing.expectEqual({over: '9000!!!'}, json);
+  });
+</script>
+
+<script id=same-origin type=module>
+  const promise1 = new Promise((resolve) => {
+    fetch('http://localhost:9582/xhr/json')
+    .then((res) => {
+      testing.expectEqual('basic', res.type);
+      return res.json()
+    })
+    .then((json) => {
+      resolve(json);
+    });
+  });
+
+  testing.async(promise1, (json) => {
+    testing.expectEqual({over: '9000!!!'}, json);
+  });
+</script>
diff --git a/src/browser/tests/legacy/fetch/headers.html b/src/browser/tests/legacy/fetch/headers.html
new file mode 100644
index 00000000..57d6ce2e
--- /dev/null
+++ b/src/browser/tests/legacy/fetch/headers.html
@@ -0,0 +1,102 @@
+<script src="../testing.js"></script>
+
+<script id=headers>
+  let headers = new Headers({"Set-Cookie": "name=world"});
+  testing.expectEqual("name=world", headers.get("set-cookie"));
+
+  let myHeaders = new Headers();
+  myHeaders.append("Content-Type", "image/jpeg"),
+  testing.expectEqual(false, myHeaders.has("Picture-Type"));
+  testing.expectEqual("image/jpeg", myHeaders.get("Content-Type"));
+
+  myHeaders.append("Content-Type", "image/png");
+  testing.expectEqual("image/jpeg, image/png", myHeaders.get("Content-Type"));
+
+  myHeaders.delete("Content-Type");
+  testing.expectEqual(null, myHeaders.get("Content-Type"));
+
+  myHeaders.set("Picture-Type", "image/svg")
+  testing.expectEqual("image/svg", myHeaders.get("Picture-Type"));
+  testing.expectEqual(true, myHeaders.has("Picture-Type"))
+
+  const originalHeaders = new Headers([["Content-Type", "application/json"], ["Authorization", "Bearer token123"]]);
+  testing.expectEqual("application/json", originalHeaders.get("Content-Type"));
+  testing.expectEqual("Bearer token123", originalHeaders.get("Authorization"));
+
+  const newHeaders = new Headers(originalHeaders);
+  testing.expectEqual("application/json", newHeaders.get("Content-Type"));
+  testing.expectEqual("Bearer token123" ,newHeaders.get("Authorization"));
+  testing.expectEqual(true ,newHeaders.has("Content-Type"));
+  testing.expectEqual(true ,newHeaders.has("Authorization"));
+  testing.expectEqual(false, newHeaders.has("X-Custom"));
+
+  newHeaders.set("X-Custom", "test-value");
+  testing.expectEqual("test-value", newHeaders.get("X-Custom"));
+  testing.expectEqual(null, originalHeaders.get("X-Custom"));
+  testing.expectEqual(false, originalHeaders.has("X-Custom"));
+</script>
+
+<script id=keys>
+  const testKeyHeaders = new Headers();
+  testKeyHeaders.set("Content-Type", "application/json");
+  testKeyHeaders.set("Authorization", "Bearer token123");
+  testKeyHeaders.set("X-Custom", "test-value");
+
+  const keys = [];
+  for (const key of testKeyHeaders.keys()) {
+      keys.push(key);
+  }
+
+  testing.expectEqual(3, keys.length);
+  testing.expectEqual(true, keys.includes("Content-Type"));
+  testing.expectEqual(true, keys.includes("Authorization"));
+  testing.expectEqual(true, keys.includes("X-Custom"));
+</script>
+
+<script id=values>
+  const testValuesHeaders = new Headers();
+  testValuesHeaders.set("Content-Type", "application/json");
+  testValuesHeaders.set("Authorization", "Bearer token123");
+  testValuesHeaders.set("X-Custom", "test-value");
+
+  const values = [];
+  for (const value of testValuesHeaders.values()) {
+      values.push(value);
+  }
+
+  testing.expectEqual(3, values.length);
+  testing.expectEqual(true, values.includes("application/json"));
+  testing.expectEqual(true, values.includes("Bearer token123"));
+  testing.expectEqual(true, values.includes("test-value"));
+</script>
+
+<script id=entries>
+  const testEntriesHeaders = new Headers();
+  testEntriesHeaders.set("Content-Type", "application/json");
+  testEntriesHeaders.set("Authorization", "Bearer token123");
+  testEntriesHeaders.set("X-Custom", "test-value");
+
+  const entries = [];
+  for (const entry of testEntriesHeaders.entries()) {
+      entries.push(entry);
+  }
+        
+  testing.expectEqual(3, entries.length);
+
+  const entryMap = new Map(entries);
+  testing.expectEqual("application/json", entryMap.get("Content-Type"));
+  testing.expectEqual("Bearer token123", entryMap.get("Authorization"));
+  testing.expectEqual("test-value", entryMap.get("X-Custom"));
+  
+  const entryKeys = Array.from(entryMap.keys());
+  testing.expectEqual(3, entryKeys.length);
+  testing.expectEqual(true, entryKeys.includes("Content-Type"));
+  testing.expectEqual(true, entryKeys.includes("Authorization"));
+  testing.expectEqual(true, entryKeys.includes("X-Custom"));
+  
+  const entryValues = Array.from(entryMap.values());
+  testing.expectEqual(3, entryValues.length);
+  testing.expectEqual(true, entryValues.includes("application/json"));
+  testing.expectEqual(true, entryValues.includes("Bearer token123"));
+  testing.expectEqual(true, entryValues.includes("test-value"))
+</script>
diff --git a/src/browser/tests/legacy/fetch/request.html b/src/browser/tests/legacy/fetch/request.html
new file mode 100644
index 00000000..7bfdfe56
--- /dev/null
+++ b/src/browser/tests/legacy/fetch/request.html
@@ -0,0 +1,22 @@
+<script src="../testing.js"></script>
+
+<script id=request>
+  let request = new Request("flower.png");
+  testing.expectEqual("http://localhost:9582/src/tests/fetch/flower.png", request.url);
+  testing.expectEqual("GET", request.method);
+
+  let request2 = new Request("https://google.com", {
+    method: "POST",
+    body: "Hello, World",
+    cache: "reload",
+    credentials: "omit",
+    headers: { "Sender": "me", "Target": "you" }
+    }
+  );
+  testing.expectEqual("https://google.com", request2.url);
+  testing.expectEqual("POST", request2.method);
+  testing.expectEqual("omit", request2.credentials);
+  testing.expectEqual("reload", request2.cache);
+  testing.expectEqual("me", request2.headers.get("SeNdEr"));
+  testing.expectEqual("you", request2.headers.get("target"));
+</script>
diff --git a/src/browser/tests/legacy/fetch/response.html b/src/browser/tests/legacy/fetch/response.html
new file mode 100644
index 00000000..f65a2fea
--- /dev/null
+++ b/src/browser/tests/legacy/fetch/response.html
@@ -0,0 +1,50 @@
+<script src="../testing.js"></script>
+
+<script id=response>
+  let response = new Response("Hello, World!");
+  testing.expectEqual(200, response.status);
+  testing.expectEqual("", response.statusText);
+  testing.expectEqual(true, response.ok);
+  testing.expectEqual("", response.url);
+  testing.expectEqual(false, response.redirected);
+
+  let response2 = new Response("Error occurred", {
+    status: 404,
+    statusText: "Not Found",
+    headers: { 
+        "Content-Type": "text/plain", 
+        "X-Custom": "test-value",
+        "Cache-Control": "no-cache"
+    }
+  });
+  testing.expectEqual(404, response2.status);
+  testing.expectEqual("Not Found", response2.statusText);
+  testing.expectEqual(false, response2.ok);
+  testing.expectEqual("text/plain", response2.headers.get("Content-Type"));
+  testing.expectEqual("test-value", response2.headers.get("X-Custom"));
+  testing.expectEqual("no-cache", response2.headers.get("cache-control"));
+        
+  let response3 = new Response("Created", { status: 201, statusText: "Created" });
+  testing.expectEqual("basic", response3.type);
+  testing.expectEqual(201, response3.status);
+  testing.expectEqual("Created", response3.statusText);
+  testing.expectEqual(true, response3.ok);
+
+  let nullResponse = new Response(null);
+  testing.expectEqual(200, nullResponse.status);
+  testing.expectEqual("", nullResponse.statusText);
+
+  let emptyResponse = new Response("");
+  testing.expectEqual(200, emptyResponse.status);
+</script>
+
+<script id=json type=module>
+  const promise1 = new Promise((resolve) => {
+    let response = new Response('[]');
+    response.json().then(resolve)
+  });
+
+  testing.async(promise1, (json) => {
+    testing.expectEqual([], json);
+  });
+</script>
diff --git a/src/browser/tests/legacy/file/blob.html b/src/browser/tests/legacy/file/blob.html
new file mode 100644
index 00000000..343fd32b
--- /dev/null
+++ b/src/browser/tests/legacy/file/blob.html
@@ -0,0 +1,125 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=Blob/Blob.text>
+  {
+    const parts = ["\r\nthe quick brown\rfo\rx\r", "\njumps over\r\nthe\nlazy\r", "\ndog"];
+    // "transparent" ending should not modify the final buffer.
+    const blob = new Blob(parts, { type: "text/html" });
+
+    const expected = parts.join("");
+    testing.expectEqual(expected.length, blob.size);
+    testing.expectEqual("text/html", blob.type);
+    testing.async(blob.text(), result => testing.expectEqual(expected, result));
+  }
+
+  {
+    const parts = ["\rhello\r", "\nwor\r\nld"];
+    // "native" ending should modify the final buffer.
+    const blob = new Blob(parts, { endings: "native" });
+
+    const expected = "\nhello\n\nwor\nld";
+    testing.expectEqual(expected.length, blob.size);
+    testing.async(blob.text(), result => testing.expectEqual(expected, result));
+
+    testing.async(blob.arrayBuffer(), result => testing.expectEqual(true, result instanceof ArrayBuffer));
+  }
+</script>
+
+<script id=Blob.stream>
+  {
+    const parts = ["may", "thy", "knife", "chip", "and", "shatter"];
+    const blob = new Blob(parts);
+    const reader = blob.stream().getReader();
+
+    testing.async(reader.read(), ({ done, value }) => {
+      const expected = new Uint8Array([109, 97, 121, 116, 104, 121, 107, 110,
+                                       105, 102, 101, 99, 104, 105, 112, 97,
+                                       110, 100, 115, 104, 97, 116, 116, 101,
+                                       114]);
+      testing.expectEqual(false, done);
+      testing.expectEqual(true, value instanceof Uint8Array);
+      testing.expectEqual(expected, value);
+    });
+  }
+</script>
+
+<script id=Blob.arrayBuffer/Blob.slice>
+  {
+    const parts = ["la", "symphonie", "des", "éclairs"];
+    const blob = new Blob(parts);
+    testing.async(blob.arrayBuffer(), result => testing.expectEqual(true, result instanceof ArrayBuffer));
+
+    let temp = blob.slice(0);
+    testing.expectEqual(blob.size, temp.size);
+    testing.async(temp.text(), result => {
+      testing.expectEqual("lasymphoniedeséclairs", result);
+    });
+
+    temp = blob.slice(-4, -2, "custom");
+    testing.expectEqual(2, temp.size);
+    testing.expectEqual("custom", temp.type);
+    testing.async(temp.text(), result => testing.expectEqual("ai", result));
+
+    temp = blob.slice(14);
+    testing.expectEqual(8, temp.size);
+    testing.async(temp.text(), result => testing.expectEqual("éclairs", result));
+
+    temp = blob.slice(6, -10, "text/eclair");
+    testing.expectEqual(6, temp.size);
+    testing.expectEqual("text/eclair", temp.type);
+    testing.async(temp.text(), result => testing.expectEqual("honied", result));
+  }
+</script>
+
+<!-- Firefox and Safari only -->
+<script id=Blob.bytes>
+  {
+    const parts = ["light ", "panda ", "rocks ", "!"];
+    const blob = new Blob(parts);
+
+    testing.async(blob.bytes(), result => {
+      const expected = new Uint8Array([108, 105, 103, 104, 116, 32, 112, 97,
+                                       110, 100, 97, 32, 114, 111, 99, 107, 115,
+                                       32, 33]);
+      testing.expectEqual(true, result instanceof Uint8Array);
+      testing.expectEqual(expected, result);
+    });
+  }
+
+  // Test for SIMD.
+  {
+    const parts = [
+      "\rThe opened package\r\nof potato\nchi\rps",
+      "held the\r\nanswer to the\r mystery. Both det\rectives looke\r\rd\r",
+      "\rat it but failed to realize\nit was\r\nthe\rkey\r\n",
+      "\r\nto solve the \rcrime.\r"
+    ];
+
+    const blob = new Blob(parts, { type: "text/html", endings: "native" });
+    testing.expectEqual(161, blob.size);
+    testing.expectEqual("text/html", blob.type);
+    testing.async(blob.bytes(), result => {
+      const expected = new Uint8Array([10, 84, 104, 101, 32, 111, 112, 101, 110,
+                                       101, 100, 32, 112, 97, 99, 107, 97, 103,
+                                       101, 10, 111, 102, 32, 112, 111, 116, 97,
+                                       116, 111, 10, 99, 104, 105, 10, 112, 115,
+                                       104, 101, 108, 100, 32, 116, 104, 101, 10,
+                                       97, 110, 115, 119, 101, 114, 32, 116, 111,
+                                       32, 116, 104, 101, 10, 32, 109, 121, 115,
+                                       116, 101, 114, 121, 46, 32, 66, 111, 116,
+                                       104, 32, 100, 101, 116, 10, 101, 99, 116,
+                                       105, 118, 101, 115, 32, 108, 111, 111, 107,
+                                       101, 10, 10, 100, 10, 10, 97, 116, 32, 105,
+                                       116, 32, 98, 117, 116, 32, 102, 97, 105, 108,
+                                       101, 100, 32, 116, 111, 32, 114, 101, 97,
+                                       108, 105, 122, 101, 10, 105, 116, 32, 119, 97,
+                                       115, 10, 116, 104, 101, 10, 107, 101, 121,
+                                       10, 10, 116, 111, 32, 115, 111, 108, 118, 101,
+                                       32, 116, 104, 101, 32, 10, 99, 114, 105, 109,
+                                       101, 46, 10]);
+      testing.expectEqual(true, result instanceof Uint8Array);
+      testing.expectEqual(expected, result);
+    });
+  }
+</script>
diff --git a/src/browser/tests/legacy/file/file.html b/src/browser/tests/legacy/file/file.html
new file mode 100644
index 00000000..05f23ad7
--- /dev/null
+++ b/src/browser/tests/legacy/file/file.html
@@ -0,0 +1,7 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=file>
+  let f = new File();
+  testing.expectEqual(true, f instanceof File);
+</script>
diff --git a/src/browser/tests/legacy/html/abort_controller.html b/src/browser/tests/legacy/html/abort_controller.html
new file mode 100644
index 00000000..fc5a1cdf
--- /dev/null
+++ b/src/browser/tests/legacy/html/abort_controller.html
@@ -0,0 +1,41 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=abortController>
+  var a1 = new AbortController();
+
+  var s1 = a1.signal;
+  testing.expectEqual(undefined, s1.throwIfAborted());
+  testing.expectEqual(undefined, s1.reason);
+
+  let target;;
+  let called = 0;
+  s1.addEventListener('abort', (e) => {
+    called += 1;
+    target = e.target;
+  });
+
+  a1.abort();
+  testing.expectEqual(true, s1.aborted)
+  testing.expectEqual(s1, target)
+  testing.expectEqual('AbortError', s1.reason)
+  testing.expectEqual(1, called)
+</script>
+
+<script id=abort>
+  var s2 = AbortSignal.abort('over 9000');
+  testing.expectEqual(true, s2.aborted);
+  testing.expectEqual('over 9000', s2.reason);
+  testing.expectEqual('AbortError', AbortSignal.abort().reason);
+</script>
+
+<script id=timeout>
+  var s3 = AbortSignal.timeout(10);
+  testing.eventually(() => {
+    testing.expectEqual(true, s3.aborted);
+    testing.expectEqual('TimeoutError', s3.reason);
+    testing.expectError('Error: TimeoutError', () => {
+      s3.throwIfAborted()
+    });
+  });
+</script>
diff --git a/src/browser/tests/legacy/html/canvas.html b/src/browser/tests/legacy/html/canvas.html
new file mode 100644
index 00000000..ab076487
--- /dev/null
+++ b/src/browser/tests/legacy/html/canvas.html
@@ -0,0 +1,29 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=canvas>
+{
+  const element = document.createElement("canvas");
+  const ctx = element.getContext("2d");
+  testing.expectEqual(true, ctx instanceof CanvasRenderingContext2D);
+  // We can't really test this but let's try to call it at least.
+  ctx.fillRect(0, 0, 0, 0);
+}
+</script>
+
+<script id=canvas#fillStyle>
+{
+  const element = document.createElement("canvas");
+  const ctx = element.getContext("2d");
+
+  // Black by default.
+  testing.expectEqual(ctx.fillStyle, "#000000");
+  ctx.fillStyle = "red";
+  testing.expectEqual(ctx.fillStyle, "#ff0000");
+  ctx.fillStyle = "rebeccapurple";
+  testing.expectEqual(ctx.fillStyle, "#663399");
+  // No changes made if color is invalid.
+  ctx.fillStyle = "invalid-color";
+  testing.expectEqual(ctx.fillStyle, "#663399");
+}
+</script>
diff --git a/src/browser/tests/legacy/html/dataset.html b/src/browser/tests/legacy/html/dataset.html
new file mode 100644
index 00000000..8eff6927
--- /dev/null
+++ b/src/browser/tests/legacy/html/dataset.html
@@ -0,0 +1,30 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<div id=x data-power="over 9000" data-empty data-some-long-key=ok></div>
+
+<script id=dataset>
+  let el1 = document.createElement('div');
+  testing.expectEqual(undefined, el1.dataset.x);
+
+  el1.dataset.x = '123';
+  testing.expectEqual(true, delete el1.dataset.x);
+  testing.expectEqual(undefined, el1.dataset.x);
+  // yes, this is right
+  testing.expectEqual(true, delete el1.dataset.other);
+
+  let ds1 = el1.dataset;
+  ds1.helloWorld = 'yes';
+  testing.expectEqual('yes', el1.getAttribute('data-hello-world'));
+  el1.setAttribute('data-this-will-work', 'positive');
+  testing.expectEqual('positive', ds1.thisWillWork);
+</script>
+
+<script id=element>
+  let div = $('#x');
+  testing.expectEqual(undefined, div.dataset.nope);
+  testing.expectEqual('over 9000', div.dataset.power);
+  testing.expectEqual('', div.dataset.empty);
+  testing.expectEqual('ok', div.dataset.someLongKey);
+  testing.expectEqual(true, delete div.dataset.power);
+  testing.expectEqual(undefined, div.dataset.power);
+</script>
diff --git a/src/browser/tests/legacy/html/document.html b/src/browser/tests/legacy/html/document.html
new file mode 100644
index 00000000..cc02f7c6
--- /dev/null
+++ b/src/browser/tests/legacy/html/document.html
@@ -0,0 +1,85 @@
+<!DOCTYPE html>
+<html>
+  <body>
+    <div id=content><a id=link href=#></a></div>
+  </body>
+</html>
+
+<script src="../testing.js"></script>
+
+<script id=document>
+  testing.expectEqual('HTMLDocument', document.__proto__.constructor.name);
+  testing.expectEqual('Document', document.__proto__.__proto__.constructor.name);
+  testing.expectEqual('body', document.body.localName);
+
+  testing.expectEqual('localhost:9582', document.domain);
+  testing.expectEqual('', document.referrer);
+  testing.expectEqual('', document.title);
+  testing.expectEqual('body', document.body.localName);
+  testing.expectEqual('head', document.head.localName);
+  testing.expectEqual(0, document.images.length);
+  testing.expectEqual(0, document.embeds.length);
+  testing.expectEqual(0, document.plugins.length);
+  testing.expectEqual(2, document.scripts.length);
+  testing.expectEqual(0, document.forms.length);
+  testing.expectEqual(1, document.links.length);
+  testing.expectEqual(0, document.applets.length);
+  testing.expectEqual(0, document.anchors.length);
+  testing.expectEqual(7, document.all.length);
+  testing.expectEqual('document', document.currentScript.id);
+
+  document.title = 'foo';
+  testing.expectEqual('foo', document.title);
+  document.title = '';
+
+  document.getElementById('link').setAttribute('name', 'foo');
+  let list = document.getElementsByName('foo');
+  testing.expectEqual(1, list.length);
+
+  testing.expectEqual('', document.cookie);
+  document.cookie = 'name=Oeschger;';
+  document.cookie = 'favorite_food=tripe;';
+
+  testing.expectEqual('name=Oeschger; favorite_food=tripe', document.cookie);
+  // "" should be returned, but the framework overrules it atm
+  document.cookie = 'IgnoreMy=Ghost; HttpOnly';
+  testing.expectEqual('name=Oeschger; favorite_food=tripe', document.cookie);
+
+  // Return null since we only return elements when they have previously been localized
+  testing.expectEqual(null, document.elementFromPoint(2.5, 2.5));
+  testing.expectEqual([], document.elementsFromPoint(2.5, 2.5));
+
+  let div1 = document.createElement('div');
+  document.body.appendChild(div1);
+  div1.getClientRects(); // clal this to position it
+  testing.expectEqual('[object HTMLDivElement]', document.elementFromPoint(2.5, 2.5).toString());
+
+  let elems = document.elementsFromPoint(2.5, 2.5);
+  testing.expectEqual(3, elems.length);
+  testing.expectEqual('[object HTMLDivElement]', elems[0].toString());
+  testing.expectEqual('[object HTMLBodyElement]', elems[1].toString());
+  testing.expectEqual('[object HTMLHtmlElement]', elems[2].toString());
+
+  let a = document.createElement('a');
+  a.href = "https://lightpanda.io";
+  document.body.appendChild(a);
+  // Note this will be placed after the div of previous test
+  a.getClientRects();
+
+  let a_again = document.elementFromPoint(7.5, 0.5);
+  testing.expectEqual('[object HTMLAnchorElement]', a_again.toString());
+  testing.expectEqual('https://lightpanda.io', a_again.href);
+
+  let a_agains = document.elementsFromPoint(7.5, 0.5);
+  testing.expectEqual('https://lightpanda.io', a_agains[0].href);
+
+
+  testing.expectEqual(true, !document.all);
+  testing.expectEqual(false, !!document.all);
+  testing.expectEqual('[object HTMLScriptElement]', document.all(5).toString());
+  testing.expectEqual('[object HTMLDivElement]', document.all('content').toString());
+
+
+  testing.expectEqual(document, document.defaultView.document );
+  testing.expectEqual('loading', document.readyState);
+</script>
diff --git a/src/browser/tests/legacy/html/element.html b/src/browser/tests/legacy/html/element.html
new file mode 100644
index 00000000..4de1f058
--- /dev/null
+++ b/src/browser/tests/legacy/html/element.html
@@ -0,0 +1,53 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<div id=content>a<strong>b</strong>cc</div>
+<script id=inner>
+  const content = $('#content');
+  testing.expectEqual('a<strong>b</strong>cc', content.innerHTML);
+  testing.expectEqual('abcc', content.innerText);
+  content. innerText = 'foo';
+
+  testing.expectEqual('foo', content.innerHTML);
+  testing.expectEqual('foo', content.innerText);
+</script>
+
+<script id=addEventListene>
+  let click_count = 0;
+  content.addEventListener('click', function() { click_count++ });
+  content.click()
+  testing.expectEqual(1, click_count);
+</script>
+
+<script id=style>
+  let style = content.style;
+  style.cssText = 'color: red; font-size: 12px; margin: 5px !important';
+  testing.expectEqual(3, style.length);
+  style.setProperty('background-color', 'blue')
+  testing.expectEqual('blue', style.getPropertyValue('background-color'));
+  testing.expectEqual(4, style.length);
+</script>
+
+<script id=a>
+  let a = document.createElement('a');
+  testing.expectEqual('', a.href);
+  testing.expectEqual('', a.host);
+  a.href = 'about';
+  testing.expectEqual('http://localhost:9582/src/tests/html/about', a.href);
+</script>
+
+<script id=focus>
+  // detached node cannot be focused
+  const focused = document.activeElement;
+  document.createElement('a').focus();
+  testing.expectEqual(focused, document.activeElement);
+</script>
+
+<script id=link>
+  let l2 = document.createElement('link');
+  testing.expectEqual('', l2.href);
+  l2.href = 'https://lightpanda.io/opensource-browser/15';
+  testing.expectEqual('https://lightpanda.io/opensource-browser/15', l2.href);
+
+  l2.href = '/over/9000';
+  testing.expectEqual('http://localhost:9582/over/9000', l2.href);
+</script>
diff --git a/src/browser/tests/legacy/html/error_event.html b/src/browser/tests/legacy/html/error_event.html
new file mode 100644
index 00000000..be2c56a4
--- /dev/null
+++ b/src/browser/tests/legacy/html/error_event.html
@@ -0,0 +1,25 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=ErrorEvent>
+  let e1 = new ErrorEvent('err1')
+  testing.expectEqual('', e1.message);
+  testing.expectEqual('', e1.filename);
+  testing.expectEqual(0, e1.lineno);
+  testing.expectEqual(0, e1.colno);
+  testing.expectEqual(undefined, e1.error);
+
+  let e2 = new ErrorEvent('err1', {
+     message: 'm1',
+     filename: 'fx19',
+     lineno: 443,
+     colno: 8999,
+     error: 'under 9000!',
+   });
+
+  testing.expectEqual('m1', e2.message);
+  testing.expectEqual('fx19', e2.filename);
+  testing.expectEqual(443, e2.lineno);
+  testing.expectEqual(8999, e2.colno);
+  testing.expectEqual('under 9000!', e2.error);
+</script>
diff --git a/src/browser/tests/legacy/html/history/history.html b/src/browser/tests/legacy/html/history/history.html
new file mode 100644
index 00000000..fbb7dd95
--- /dev/null
+++ b/src/browser/tests/legacy/html/history/history.html
@@ -0,0 +1,37 @@
+<!DOCTYPE html>
+<script src="../../testing.js"></script>
+
+<script id=history>
+    testing.expectEqual('auto', history.scrollRestoration);
+
+    history.scrollRestoration = 'manual';
+    testing.expectEqual('manual', history.scrollRestoration);
+
+    history.scrollRestoration = 'auto';
+    testing.expectEqual('auto', history.scrollRestoration);
+    testing.expectEqual(null, history.state)
+
+    history.pushState({ testInProgress: true }, null, 'http://127.0.0.1:9582/src/tests/html/history/history_after_nav.html');
+    testing.expectEqual({ testInProgress: true }, history.state);
+
+    history.pushState({ testInProgress: false }, null, 'http://127.0.0.1:9582/xhr/json');
+    history.replaceState({ "new": "field", testComplete: true }, null);
+
+    let state = { "new": "field", testComplete: true };
+    testing.expectEqual(state, history.state);
+
+    let popstateEventFired = false;
+    let popstateEventState = null;
+
+    window.addEventListener('popstate', (event) => {
+        popstateEventFired = true;
+        popstateEventState = event.state;
+    });
+
+    testing.eventually(() => {
+      testing.expectEqual(true, popstateEventFired);
+      testing.expectEqual(state, popstateEventState);
+    })
+
+    history.back();
+</script>
diff --git a/src/browser/tests/legacy/html/history/history2.html b/src/browser/tests/legacy/html/history/history2.html
new file mode 100644
index 00000000..83dd809a
--- /dev/null
+++ b/src/browser/tests/legacy/html/history/history2.html
@@ -0,0 +1,26 @@
+<!DOCTYPE html>
+<script src="../../testing.js"></script>
+
+<script id=history2>
+    history.pushState(
+      {"new": "field", testComplete: true },
+      null,
+      'http://127.0.0.1:9582/src/tests/html/history/history_after_nav.html'
+    );
+
+    let popstateEventFired = false;
+    let popstateEventState = null;
+
+    // uses the window event listener.
+    window.onpopstate = (event) => {
+        popstateEventFired = true;
+        popstateEventState = event.state;
+    };
+    
+    testing.eventually(() => {
+      testing.expectEqual(true, popstateEventFired);
+      testing.expectEqual(true, popstateEventState.testComplete);
+    })
+
+    history.back();
+</script>
diff --git a/src/browser/tests/legacy/html/history/history_after_nav.html b/src/browser/tests/legacy/html/history/history_after_nav.html
new file mode 100644
index 00000000..d9e4e66d
--- /dev/null
+++ b/src/browser/tests/legacy/html/history/history_after_nav.html
@@ -0,0 +1,6 @@
+<!DOCTYPE html>
+<script src="../../testing.js"></script>
+
+<script id=history2>
+    testing.expectEqual(true, history.state && history.state.testInProgress);
+</script>
diff --git a/src/browser/tests/legacy/html/image.html b/src/browser/tests/legacy/html/image.html
new file mode 100644
index 00000000..1e3f6aff
--- /dev/null
+++ b/src/browser/tests/legacy/html/image.html
@@ -0,0 +1,32 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=image>
+  img = new Image();
+  testing.expectEqual(0, img.width);
+  testing.expectEqual(0, img.height);
+
+  img = new Image(4);
+  testing.expectEqual(4, img.width);
+  testing.expectEqual(0, img.height);
+
+  img = new Image(5, 6);
+  testing.expectEqual(5, img.width);
+  testing.expectEqual(6, img.height);
+
+  let fruit = new Image
+  testing.expectEqual(0, fruit.width);
+  fruit.width = 5;
+  testing.expectEqual(5, fruit.width);
+  fruit.width = '15';
+  testing.expectEqual(15, fruit.width);
+  fruit.width = 'apple';
+  testing.expectEqual(0, fruit.width);
+
+  let lyric = new Image
+  testing.expectEqual('', lyric.src);
+  lyric.src = 'okay';
+  testing.expectEqual('okay', lyric.src);
+  lyric.src = 15;
+  testing.expectEqual('15', lyric.src);
+</script>
diff --git a/src/browser/tests/legacy/html/input.html b/src/browser/tests/legacy/html/input.html
new file mode 100644
index 00000000..4a7e991a
--- /dev/null
+++ b/src/browser/tests/legacy/html/input.html
@@ -0,0 +1,111 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<form action="test.php" target="_blank" id=form>
+  <p>
+    <label>First name: <input type="text" name="first-name" id=input /></label>
+  </p>
+</form>
+
+<script id=input_properties>
+  let input = document.createElement('input');
+
+  testing.expectEqual(null, input.form);
+  input.form = 'foo';
+  testing.expectEqual(null, input.form);
+
+  testing.expectEqual('', input.name);
+  input.name = 'leto';
+  testing.expectEqual('leto', input.name);
+
+  testing.expectEqual('', input.accept);
+  input.accept = 'anything';
+  testing.expectEqual('anything', input.accept);
+
+  testing.expectEqual('', input.alt);
+  input.alt = 'x1';
+  testing.expectEqual('x1', input.alt);
+
+  testing.expectEqual(false, input.disabled);
+  input.disabled = true;
+  testing.expectEqual(true, input.disabled);
+  input.disabled = false;
+  testing.expectEqual(false, input.disabled);
+
+  testing.expectEqual(false, input.readOnly);
+  input.readOnly = true;
+  testing.expectEqual(true, input.readOnly);
+  input.readOnly = false;
+  testing.expectEqual(false, input.readOnly);
+
+  testing.expectEqual(-1, input.maxLength);
+  input.maxLength = 5;
+  testing.expectEqual(5, input.maxLength);
+  input.maxLength = 'banana';
+  testing.expectEqual(0, input.maxLength);
+  testing.expectError('Error: NegativeValueNotAllowed', () => { input.maxLength = -45;});
+
+  testing.expectEqual(20, input.size);
+  input.size = 5;
+  testing.expectEqual(5, input.size);
+  input.size = -449;
+  testing.expectEqual(20, input.size);
+  testing.expectError('Error: ZeroNotAllowed', () => { input.size = 0; });
+
+  testing.expectEqual('', input.src);
+  input.src = 'foo'
+  testing.expectEqual('http://localhost:9582/src/tests/html/foo', input.src);
+  input.src = '-3'
+  testing.expectEqual('http://localhost:9582/src/tests/html/-3', input.src);
+  input.src = ''
+  testing.expectEqual('http://localhost:9582/src/tests/html/input.html', input.src);
+
+  testing.expectEqual('text', input.type);
+  input.type = 'checkbox';
+  testing.expectEqual('checkbox', input.type);
+  input.type = '5';
+  testing.expectEqual('text', input.type);
+</script>
+
+<script id=related>
+  let input_checked = document.createElement('input')
+  testing.expectEqual(false, input_checked.defaultChecked);
+  testing.expectEqual(false, input_checked.checked);
+
+  input_checked.defaultChecked = true;
+  testing.expectEqual(true, input_checked.defaultChecked);
+  testing.expectEqual(true, input_checked.checked);
+
+  input_checked.checked = false;
+  testing.expectEqual(true, input_checked.defaultChecked);
+  testing.expectEqual(false, input_checked.checked);
+
+  input_checked.defaultChecked = true;
+  testing.expectEqual(false, input_checked.checked);
+</script>
+
+<script id=defaultValue>
+  testing.expectEqual('', input.defaultValue);
+  testing.expectEqual('', input.value);
+
+  input.defaultValue = 3.1;
+  testing.expectEqual('3.1', input.defaultValue);
+  testing.expectEqual('3.1', input.value)
+
+  input.value = 'mango';
+  testing.expectEqual('3.1', input.defaultValue);
+  testing.expectEqual('mango', input.value);
+
+  input.defaultValue = true;
+  testing.expectEqual('mango', input.value);
+</script>
+
+<script id=form>
+  const form = $('#form');
+  input = $('#input');
+  testing.expectEqual(form, input.form);
+
+  // invalid
+  input.form = 'foo';
+  testing.expectEqual(form, input.form);
+</script>
diff --git a/src/browser/tests/legacy/html/link.html b/src/browser/tests/legacy/html/link.html
new file mode 100644
index 00000000..15da6461
--- /dev/null
+++ b/src/browser/tests/legacy/html/link.html
@@ -0,0 +1,60 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<a id=link href=foo>OK</a>
+
+<script id=link>
+  let link = $('#link');
+  testing.expectEqual('', link.target);
+  link.target = '_blank';
+  testing.expectEqual('_blank', link.target);
+  link.target = '';
+
+  testing.expectEqual('foo', link.href);
+  link.href = 'https://lightpanda.io/';
+  testing.expectEqual('https://lightpanda.io/', link.href);
+
+  testing.expectEqual('https://lightpanda.io', link.origin);
+
+  link.host = 'lightpanda.io:443';
+  testing.expectEqual('lightpanda.io', link.host);
+  testing.expectEqual('', link.port);
+  testing.expectEqual('lightpanda.io', link.hostname);
+
+  link.host = 'lightpanda.io';
+  testing.expectEqual('lightpanda.io', link.host);
+  testing.expectEqual('', link.port);
+  testing.expectEqual('lightpanda.io', link.hostname);
+
+  testing.expectEqual('lightpanda.io', link.host);
+  testing.expectEqual('lightpanda.io', link.hostname);
+  link.hostname = 'foo.bar';
+  testing.expectEqual('https://foo.bar/', link.href);
+
+  testing.expectEqual('', link.search);
+  link.search = 'q=bar';
+  testing.expectEqual('?q=bar', link.search);
+  testing.expectEqual('https://foo.bar/?q=bar', link.href);
+
+  testing.expectEqual('', link.hash);
+  link.hash = 'frag';
+  testing.expectEqual('#frag', link.hash);
+  testing.expectEqual('https://foo.bar/?q=bar#frag', link.href);
+
+  testing.expectEqual('', link.port);
+  link.port = '443';
+  testing.expectEqual('foo.bar', link.host);
+  testing.expectEqual('foo.bar', link.hostname);
+  testing.expectEqual('https://foo.bar/?q=bar#frag', link.href);
+  link.port = null;
+  testing.expectEqual('https://foo.bar/?q=bar#frag', link.href);
+
+  testing.expectEqual('foo', link.href = 'foo');
+
+  testing.expectEqual('', link.type);
+  link.type = 'text/html';
+  testing.expectEqual('text/html', link.type);
+
+  testing.expectEqual('OK', link.text);
+  link.text = 'foo';
+  testing.expectEqual('foo', link.text);
+</script>
diff --git a/src/browser/tests/legacy/html/location.html b/src/browser/tests/legacy/html/location.html
new file mode 100644
index 00000000..a5de3ba8
--- /dev/null
+++ b/src/browser/tests/legacy/html/location.html
@@ -0,0 +1,33 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=location>
+  testing.expectEqual('http://localhost:9582/src/tests/html/location.html', location.href);
+  testing.expectEqual('http://localhost:9582/src/tests/html/location.html', document.location.href);
+
+  testing.expectEqual("localhost:9582", location.host);
+  testing.expectEqual("localhost", location.hostname);
+  testing.expectEqual("http://localhost:9582", location.origin);
+  testing.expectEqual("/src/tests/html/location.html", location.pathname);
+  testing.expectEqual("", location.hash);
+  testing.expectEqual("9582", location.port);
+  testing.expectEqual("", location.search);
+</script>
+
+<script id=location_hash>
+  location.hash = "";
+  testing.expectEqual("", location.hash);
+  testing.expectEqual('http://localhost:9582/src/tests/html/location.html', location.href);
+
+  location.hash = "#abcdef";
+  testing.expectEqual("#abcdef", location.hash);
+  testing.expectEqual('http://localhost:9582/src/tests/html/location.html#abcdef', location.href);
+
+  location.hash = "xyzxyz";
+  testing.expectEqual("#xyzxyz", location.hash);
+  testing.expectEqual('http://localhost:9582/src/tests/html/location.html#xyzxyz', location.href);
+
+  location.hash = "";
+  testing.expectEqual("", location.hash);
+  testing.expectEqual('http://localhost:9582/src/tests/html/location.html', location.href);
+</script>
diff --git a/src/browser/tests/legacy/html/navigation/navigation.html b/src/browser/tests/legacy/html/navigation/navigation.html
new file mode 100644
index 00000000..24efe6c7
--- /dev/null
+++ b/src/browser/tests/legacy/html/navigation/navigation.html
@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<script src="../../testing.js"></script>
+
+<script id=navigation>
+    testing.expectEqual('object', typeof navigation);
+    testing.expectEqual('object', typeof navigation.currentEntry);
+    
+    testing.expectEqual('string', typeof navigation.currentEntry.id);
+    testing.expectEqual('string', typeof navigation.currentEntry.key);
+    testing.expectEqual('string', typeof navigation.currentEntry.url);
+
+    const currentIndex = navigation.currentEntry.index;
+
+    navigation.navigate(
+        'http://localhost:9582/src/tests/html/navigation/navigation2.html',
+        { state: { currentIndex: currentIndex, navTestInProgress: true } }
+    );
+</script>
diff --git a/src/browser/tests/legacy/html/navigation/navigation2.html b/src/browser/tests/legacy/html/navigation/navigation2.html
new file mode 100644
index 00000000..b16fa917
--- /dev/null
+++ b/src/browser/tests/legacy/html/navigation/navigation2.html
@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<script src="../../testing.js"></script>
+
+<script id=navigation2>
+    const state = navigation.currentEntry.getState();
+    testing.expectEqual(true, state.navTestInProgress);
+    testing.expectEqual(state.currentIndex + 1, navigation.currentEntry.index);
+</script>
diff --git a/src/browser/tests/legacy/html/navigation/navigation_currententrychange.html b/src/browser/tests/legacy/html/navigation/navigation_currententrychange.html
new file mode 100644
index 00000000..c84bcbad
--- /dev/null
+++ b/src/browser/tests/legacy/html/navigation/navigation_currententrychange.html
@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+<script src="../../testing.js"></script>
+
+<script id=navigation_currententrychange>
+    let currentEntryChanged = false;
+
+    navigation.addEventListener("currententrychange", () => {
+      currentEntryChanged = true;
+    });
+
+    // Doesn't fully navigate if same document.
+    location.href = location.href + "#1";
+
+    testing.expectEqual(true, currentEntryChanged);
+</script>
diff --git a/src/browser/tests/legacy/html/navigator.html b/src/browser/tests/legacy/html/navigator.html
new file mode 100644
index 00000000..fb2b3ffe
--- /dev/null
+++ b/src/browser/tests/legacy/html/navigator.html
@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=navigator>
+  testing.expectEqual('Lightpanda/1.0',  navigator.userAgent);
+  testing.expectEqual('1.0',  navigator.appVersion);
+  testing.expectEqual('en-US',  navigator.language);
+</script>
diff --git a/src/browser/tests/legacy/html/screen.html b/src/browser/tests/legacy/html/screen.html
new file mode 100644
index 00000000..82f4b71c
--- /dev/null
+++ b/src/browser/tests/legacy/html/screen.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=screen>
+  let screen = window.screen;
+  testing.expectEqual(1920, screen.width);
+  testing.expectEqual(1080, screen.height);
+
+  let orientation = screen.orientation;
+  testing.expectEqual(0, orientation.angle);
+  testing.expectEqual('landscape-primary', orientation.type);
+
+  // this shouldn't crash (it used to)
+  screen.addEventListener('change', () => {});
+</script>
+
+<script id=orientation>
+  screen.orientation.addEventListener('change', () => {})
+  // above shouldn't crash (it used to)
+  testing.skip();
+</script>
diff --git a/src/browser/tests/legacy/html/script/dynamic_import.html b/src/browser/tests/legacy/html/script/dynamic_import.html
new file mode 100644
index 00000000..ddaa19a2
--- /dev/null
+++ b/src/browser/tests/legacy/html/script/dynamic_import.html
@@ -0,0 +1,32 @@
+<!DOCTYPE html>
+
+<script src="../../testing.js"></script>
+
+<script id=dynamic_import type=module>
+  const promise1 = new Promise((resolve) => {
+    Promise.all([
+      import('./import.js'),
+      import('./import.js'),
+      import('./import.js'),
+      import('./import.js'),
+      import('./import.js'),
+      import('./import.js'),
+      import('./import2.js'),
+      import('./import.js'),
+      import('./import.js'),
+    ]).then(resolve);
+  });
+
+  testing.async(promise1, (res) => {
+    testing.expectEqual(9, res.length);
+    testing.expectEqual('hello', res[0].greeting);
+    testing.expectEqual('hello', res[1].greeting);
+    testing.expectEqual('hello', res[2].greeting);
+    testing.expectEqual('hello', res[3].greeting);
+    testing.expectEqual('hello', res[4].greeting);
+    testing.expectEqual('hello', res[5].greeting);
+    testing.expectEqual('world', res[6].greeting);
+    testing.expectEqual('hello', res[7].greeting);
+    testing.expectEqual('hello', res[8].greeting);
+  });
+</script>
diff --git a/src/browser/tests/legacy/html/script/import.html b/src/browser/tests/legacy/html/script/import.html
new file mode 100644
index 00000000..7a4037af
--- /dev/null
+++ b/src/browser/tests/legacy/html/script/import.html
@@ -0,0 +1,15 @@
+<!DOCTYPE html>
+
+<script src="../../testing.js"></script>
+
+<script id=import type=module>
+  import * as im from './import.js';
+  testing.expectEqual('hello', im.greeting);
+</script>
+
+<script id=cached type=module>
+  // hopefully cached, who knows, no real way to assert this
+  // but at least it works.
+  import * as im from './import.js';
+  testing.expectEqual('hello', im.greeting);
+</script>
diff --git a/src/browser/tests/legacy/html/script/import.js b/src/browser/tests/legacy/html/script/import.js
new file mode 100644
index 00000000..fb140c03
--- /dev/null
+++ b/src/browser/tests/legacy/html/script/import.js
@@ -0,0 +1,2 @@
+let greeting = 'hello';
+export {greeting as 'greeting'};
diff --git a/src/browser/tests/legacy/html/script/import2.js b/src/browser/tests/legacy/html/script/import2.js
new file mode 100644
index 00000000..328b8943
--- /dev/null
+++ b/src/browser/tests/legacy/html/script/import2.js
@@ -0,0 +1,2 @@
+let greeting = 'world';
+export {greeting as 'greeting'};
diff --git a/src/browser/tests/legacy/html/script/importmap.html b/src/browser/tests/legacy/html/script/importmap.html
new file mode 100644
index 00000000..973d5080
--- /dev/null
+++ b/src/browser/tests/legacy/html/script/importmap.html
@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+
+<script src="../../testing.js"></script>
+
+<script type=importmap>
+    {
+      "imports": {
+        "core": "./import.js"
+      }
+    }
+</script>
+
+<script id=use_importmap type=module>
+  import * as im from 'core';
+  testing.expectEqual('hello', im.greeting);
+</script>
+
+<script id=cached_importmap type=module>
+  // hopefully cached, who knows, no real way to assert this
+  // but at least it works.
+  import * as im from 'core';
+  testing.expectEqual('hello', im.greeting);
+</script>
+
diff --git a/src/browser/tests/legacy/html/script/inline_defer.html b/src/browser/tests/legacy/html/script/inline_defer.html
new file mode 100644
index 00000000..ec5b44c6
--- /dev/null
+++ b/src/browser/tests/legacy/html/script/inline_defer.html
@@ -0,0 +1,28 @@
+<!DOCTYPE html>
+<head>
+  <script>
+    let dyn1_loaded = 0;
+    function loadScript(src) {
+      const script = document.createElement('script');
+      script.src = src;
+      document.getElementsByTagName("head")[0].appendChild(script)
+    }
+  </script>
+</head>
+
+<script src="../../testing.js"></script>
+
+<script defer>
+  loadScript('inline_defer.js');
+</script>
+
+<script async>
+  loadScript('inline_defer.js');
+</script>
+
+<script id=inline_defer>
+  // inline script should ignore defer and async attributes. If we don't do
+  // this correctly, we'd end up in an infinite loop
+  // https://github.com/lightpanda-io/browser/issues/1014
+  testing.eventually(() => testing.expectEqual(2, dyn1_loaded));
+</script>
diff --git a/src/browser/tests/legacy/html/script/inline_defer.js b/src/browser/tests/legacy/html/script/inline_defer.js
new file mode 100644
index 00000000..1e0ee1a4
--- /dev/null
+++ b/src/browser/tests/legacy/html/script/inline_defer.js
@@ -0,0 +1 @@
+dyn1_loaded += 1;
diff --git a/src/browser/tests/legacy/html/script/order.html b/src/browser/tests/legacy/html/script/order.html
new file mode 100644
index 00000000..7efbbef3
--- /dev/null
+++ b/src/browser/tests/legacy/html/script/order.html
@@ -0,0 +1,35 @@
+<!DOCTYPE html>
+<script src="../../testing.js"></script>
+
+<script defer id="remote_defer" src="order_defer.js"></script>
+<script defer id="remote_async" src="order_async.js"></script>
+
+<script type=module id="inline_module">
+    // inline module is always deferred.
+    list += 'g';
+    testing.expectEqual('abcdefg', list);
+</script>
+
+<script>
+    var list = '';
+</script>
+
+<script id="remote" src="order.js"></script>
+
+<script async id="inline_async">
+    // inline script ignore async
+    list += 'b';
+    testing.expectEqual('ab', list);
+</script>
+
+<script defer id="inline_defer">
+    // inline script ignore defer
+    list += 'c';
+    testing.expectEqual('abc', list);
+</script>
+
+<script id="default">
+    // simple inline script
+    list += 'd';
+    testing.expectEqual('abcd', list);
+</script>
diff --git a/src/browser/tests/legacy/html/script/order.js b/src/browser/tests/legacy/html/script/order.js
new file mode 100644
index 00000000..31e602fc
--- /dev/null
+++ b/src/browser/tests/legacy/html/script/order.js
@@ -0,0 +1,2 @@
+list += 'a';
+testing.expectEqual('a', list);
diff --git a/src/browser/tests/legacy/html/script/order_async.js b/src/browser/tests/legacy/html/script/order_async.js
new file mode 100644
index 00000000..97c9adac
--- /dev/null
+++ b/src/browser/tests/legacy/html/script/order_async.js
@@ -0,0 +1,3 @@
+list += 'f';
+testing.expectEqual('abcdef', list);
+
diff --git a/src/browser/tests/legacy/html/script/order_defer.js b/src/browser/tests/legacy/html/script/order_defer.js
new file mode 100644
index 00000000..3911b644
--- /dev/null
+++ b/src/browser/tests/legacy/html/script/order_defer.js
@@ -0,0 +1,2 @@
+list += 'e';
+testing.expectEqual('abcde', list);
diff --git a/src/browser/tests/legacy/html/script/script.html b/src/browser/tests/legacy/html/script/script.html
new file mode 100644
index 00000000..5049e4bb
--- /dev/null
+++ b/src/browser/tests/legacy/html/script/script.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<script src="../../testing.js"></script>
+
+<script id=script>
+  let script = document.createElement('script')
+  script.src = 'foo.bar';
+
+  script.async = true;
+  testing.expectEqual(true, script.async);
+  script.async = false;
+  testing.expectEqual(false, script.async);
+
+  script.defer = true;
+  testing.expectEqual(true, script.defer);
+
+  testing.expectEqual('', script.nonce);
+  script.nonce = 'hello';
+  testing.expectEqual('hello', script.nonce);
+</script>
+
+<script id=datauri src="data:text/plain;charset=utf-8;base64,dGVzdGluZy5leHBlY3RFcXVhbCh0cnVlLCB0cnVlKTs="></script>
diff --git a/src/browser/tests/legacy/html/select.html b/src/browser/tests/legacy/html/select.html
new file mode 100644
index 00000000..f18dfdab
--- /dev/null
+++ b/src/browser/tests/legacy/html/select.html
@@ -0,0 +1,80 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<form id=f1>
+ <select id=s1 name=s1><option>o1<option>o2</select>
+</form>
+<select id=s2></select>
+
+<script id=select>
+  const s = document.getElementById('s1');
+  testing.expectEqual('[object HTMLFormElement]', s.form.toString());
+  testing.expectEqual(null, document.getElementById('s2').form);
+
+  testing.expectEqual(false, s.disabled);
+  s.disabled = true;
+  testing.expectEqual(true, s.disabled);
+
+  s.disabled = false;
+  testing.expectEqual(false, s.disabled);
+
+  testing.expectEqual(false, s.multiple);
+  s.multiple = true;
+  testing.expectEqual(true, s.multiple);
+  s.multiple = false;
+  testing.expectEqual(false, s.multiple);
+
+  testing.expectEqual('s1', s.name);
+  s.name = 'sel1';
+  testing.expectEqual('sel1', s.name);
+
+  testing.expectEqual(2, s.length);
+
+  testing.expectEqual(0, s.selectedIndex);
+  s.selectedIndex = 2; // out of range
+  testing.expectEqual(-1, s.selectedIndex);
+
+  s.selectedIndex = -1;
+  testing.expectEqual(-1, s.selectedIndex);
+
+  s.selectedIndex = 0;
+  testing.expectEqual(0, s.selectedIndex);
+
+  s.selectedIndex = 1;
+  testing.expectEqual(1, s.selectedIndex);
+
+  s.selectedIndex = -323;
+  testing.expectEqual(-1, s.selectedIndex);
+
+  let options = s.options;
+  testing.expectEqual(2, options.length);
+  testing.expectEqual('o2', options.item(1).value);
+  testing.expectEqual(-1, options.selectedIndex);
+
+  let o3 = document.createElement('option');
+  o3.value = 'o3';
+  options.add(o3)
+  testing.expectEqual(3, options.length);
+  testing.expectEqual('o3', options[2].value);
+  testing.expectEqual('o3', options.item(2).value);
+
+  let o4 = document.createElement('option');
+  o4.value = 'o4';
+  options.add(o4, 1);
+  testing.expectEqual(4, options.length);
+  testing.expectEqual('o4', options.item(1).value);
+
+  let o5 = document.createElement('option');
+  o5.value = 'o5';
+  options.add(o5, o3)
+  testing.expectEqual(5, options.length);
+  testing.expectEqual('o5', options.item(3).value);
+
+  options.remove(3)
+  testing.expectEqual(4, options.length);
+  testing.expectEqual('o3', options[3].value);
+  testing.expectEqual('o3', options.item(3).value);
+
+  testing.expectEqual(undefined, options[10]);
+  testing.expectEqual(null, options.item(10));
+</script>
diff --git a/src/browser/tests/legacy/html/slot.html b/src/browser/tests/legacy/html/slot.html
new file mode 100644
index 00000000..026e13e0
--- /dev/null
+++ b/src/browser/tests/legacy/html/slot.html
@@ -0,0 +1,179 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script>
+  class LightPanda extends HTMLElement {
+    constructor() {
+      super();
+    }
+
+    connectedCallback() {
+      const shadow = this.attachShadow({ mode: "open" });
+
+      const slot1 = document.createElement('slot');
+      slot1.name = 'slot-1';
+      shadow.appendChild(slot1);
+
+      switch (this.getAttribute('mode')) {
+        case '1':
+          slot1.innerHTML = 'hello';
+          break;
+        case '2':
+          const slot2 = document.createElement('slot');
+          shadow.appendChild(slot2);
+          break;
+      }
+    }
+  }
+  window.customElements.define("lp-test", LightPanda);
+</script>
+
+<lp-test id=lp1 mode=1></lp-test>
+<lp-test id=lp2 mode=0></lp-test>
+<lp-test id=lp3 mode=0>default</lp-test>
+<lp-test id=lp4 mode=1><p slot=other>default</p></lp-test>
+<lp-test id=lp5 mode=1><p slot=slot-1>default</p> xx <b slot=slot-1>other</b></lp-test>
+<lp-test id=lp6 mode=2>More <p slot=slot-1>default2</p> <span>!!</span></lp-test>
+
+<script>
+  function assertNodes(expected, actual) {
+    actual = actual.map((n) => n.id || n.textContent)
+    testing.expectEqual(expected, actual);
+  }
+</script>
+<script id=HTMLSlotElement>
+  for (let idx of [1, 2, 3, 4]) {
+    const lp = $(`#lp${idx}`);
+    const slot = lp.shadowRoot.querySelector('slot');
+
+    assertNodes([], slot.assignedNodes());
+    assertNodes([], slot.assignedNodes({}));
+    assertNodes([], slot.assignedNodes({flatten: false}));
+    if (lp.getAttribute('mode') === '1') {
+      assertNodes(['hello'], slot.assignedNodes({flatten: true}));
+    } else {
+      assertNodes([], slot.assignedNodes({flatten: true}));
+    }
+  }
+
+  {
+    const lp5 = $('#lp5');
+    const s5 = lp5.shadowRoot.querySelector('slot');
+    assertNodes(['default', 'other'], s5.assignedNodes());
+
+    const lp6 = $('#lp6');
+    const s6 = lp6.shadowRoot.querySelectorAll('slot');
+    assertNodes(['default2'], s6[0].assignedNodes({}));
+    assertNodes(['default2'], s6[0].assignedNodes({flatten: true}));
+    assertNodes(['More ', ' ', '!!'], s6[1].assignedNodes({}));
+    assertNodes(['More ', ' ', '!!'], s6[1].assignedNodes({flatten: true}));
+
+    assertNodes(['default2'], s6[0].assignedElements({}));
+    assertNodes(['default2'], s6[0].assignedElements({flatten: true}));
+    assertNodes(['!!'], s6[1].assignedElements({}));
+    assertNodes(['!!'], s6[1].assignedElements({flatten: true}));
+  }
+</script>
+
+<lp-test id=sc1 mode=1></lp-test>
+<script id=slotChange1>
+  {
+    let calls = 0;
+    const lp = $('#sc1');
+    const slot = lp.shadowRoot.querySelector('slot');
+    slot.addEventListener('slotchange', (e) => {
+      assertNodes(['slotted'], slot.assignedNodes({}));
+      calls += 1
+    }, {});
+
+    const div = document.createElement('div');
+    div.textContent = 'Hello!';
+    div.id = 'slotted';
+    testing.expectEqual(null, div.assignedSlot);
+
+    div.setAttribute('slot', 'slot-1');
+    lp.appendChild(div);
+    testing.expectEqual(slot, div.assignedSlot);
+
+    testing.eventually(() => {
+      testing.expectEqual(1, calls)
+    });
+  }
+</script>
+
+<lp-test id=sc2 mode=1><div id=s2 slot=slot-1>hello</div></lp-test>
+<script id=slotChange2>
+  {
+    let calls = 0;
+    const lp = $('#sc2');
+    const slot = lp.shadowRoot.querySelector('slot');
+    slot.addEventListener('slotchange', (e) => {
+      assertNodes([], slot.assignedNodes({}));
+      calls += 1;
+    });
+
+    const div = $('#s2');
+    div.removeAttribute('slot');
+    testing.eventually(() => {
+      testing.expectEqual(1, calls)
+    });
+  }
+</script>
+
+<lp-test id=sc3 mode=1><div id=s3 slot=slot-1>hello</div></lp-test>
+<script id=slotChange3>
+  {
+    let calls = 0;
+    const lp = $('#sc3');
+    const slot = lp.shadowRoot.querySelector('slot');
+    slot.addEventListener('slotchange', (e) => {
+      assertNodes([], slot.assignedNodes({}));
+      calls += 1;
+    });
+
+    const div = $('#s3');
+    div.slot = 'other';
+    testing.eventually(() => {
+      testing.expectEqual(1, calls)
+    });
+  }
+</script>
+
+<lp-test id=sc4 mode=1></lp-test>
+<script id=slotChange4>
+  {
+    let calls = 0;
+    const lp = $('#sc4');
+    const slot = lp.shadowRoot.querySelector('slot');
+    slot.addEventListener('slotchange', (e) => {
+      assertNodes(['slotted'], slot.assignedNodes({}));
+      calls += 1;
+    });
+
+    const div = document.createElement('div');
+    div.id = 'slotted';
+    div.slot = 'other';
+    lp.appendChild(div);
+    div.slot = 'slot-1'
+    testing.eventually(() => {
+      testing.expectEqual(1, calls)
+    });
+  }
+</script>
+
+<lp-test id=sc5 mode=1><div id=s5 slot=slot-1>hello</div></lp-test>
+<script id=slotChange5>
+  {
+    let calls = 0;
+    const lp = $('#sc5');
+    const slot = lp.shadowRoot.querySelector('slot');
+    slot.addEventListener('slotchange', (e) => {
+      assertNodes([], slot.assignedNodes({}));
+      calls += 1;
+    });
+
+    $('#s5').remove();
+    testing.eventually(() => {
+      testing.expectEqual(1, calls)
+    });
+  }
+</script>
diff --git a/src/browser/tests/legacy/html/style.html b/src/browser/tests/legacy/html/style.html
new file mode 100644
index 00000000..6463cd81
--- /dev/null
+++ b/src/browser/tests/legacy/html/style.html
@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=style>
+  let s = document.createElement('style');
+  testing.expectEqual('text/css', s.sheet.type);
+  testing.expectEqual(false, document.createElement('style').sheet == s.sheet);
+</script>
diff --git a/src/browser/tests/legacy/html/svg.html b/src/browser/tests/legacy/html/svg.html
new file mode 100644
index 00000000..36854649
--- /dev/null
+++ b/src/browser/tests/legacy/html/svg.html
@@ -0,0 +1,38 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<svg id=lower width="200" height="100" style="border:1px solid #ccc" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 200 100">
+  <rect></rect>
+  <text x="100" y="95" font-size="14" text-anchor="middle">OVER 9000!!</text>
+</svg>
+
+<SVG ID=UPPER WIDTH="200" HEIGHT="100" STYLE="BORDER:1PX SOLID #CCC" XMLNS="http://www.w3.org/2000/svg" VIEWBOX="0 0 200 100">
+  <RECT></RECT>
+  <TEXT X="100" Y="95" FONT-SIZE="14" TEXT-ANCHOR="MIDDLE">OVER 9000!!!</TEXT>
+</SVG>
+
+<script id=svg>
+  testing.expectEqual(false, 'AString' instanceof SVGElement);
+
+  const svg1 = $('#lower');
+  testing.expectEqual('http://www.w3.org/2000/svg', svg1.getAttribute('xmlns'));
+  testing.expectEqual('http://www.w3.org/2000/svg', svg1.getAttributeNode('xmlns').value);
+  testing.expectEqual('http://www.w3.org/2000/svg', svg1.attributes.getNamedItem('xmlns').value);
+  testing.expectEqual('0 0 200 100', svg1.getAttribute('viewBox'));
+  testing.expectEqual('viewBox', svg1.getAttributeNode('viewBox').name);
+  testing.expectEqual(true, svg1.outerHTML.includes('viewBox'));
+  testing.expectEqual('svg', svg1.tagName);
+  testing.expectEqual('rect', svg1.querySelector('rect').tagName);
+  testing.expectEqual('text', svg1.querySelector('text').tagName);
+
+  const svg2 = $('#UPPER');
+  testing.expectEqual('http://www.w3.org/2000/svg', svg2.getAttribute('xmlns'));
+  testing.expectEqual('http://www.w3.org/2000/svg', svg2.getAttributeNode('xmlns').value);
+  testing.expectEqual('http://www.w3.org/2000/svg', svg2.attributes.getNamedItem('xmlns').value);
+  testing.expectEqual('0 0 200 100', svg2.getAttribute('viewBox'));
+  testing.expectEqual('viewBox', svg2.getAttributeNode('viewBox').name);
+  testing.expectEqual(true, svg2.outerHTML.includes('viewBox'));
+  testing.expectEqual('svg', svg2.tagName);
+  testing.expectEqual('rect', svg2.querySelector('rect').tagName);
+  testing.expectEqual('text', svg2.querySelector('text').tagName);
+</script>
diff --git a/src/browser/tests/legacy/html/template.html b/src/browser/tests/legacy/html/template.html
new file mode 100644
index 00000000..058c1dd3
--- /dev/null
+++ b/src/browser/tests/legacy/html/template.html
@@ -0,0 +1,38 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<div id=c></div>
+
+<script id=template>
+  let t = document.createElement('template');
+  let d = document.createElement('div');
+  d.id = 'abc';
+  t.content.append(d);
+
+  testing.expectEqual(null, document.getElementById('abc'));
+  document.getElementById('c').appendChild(t.content.cloneNode(true));
+  testing.expectEqual('abc', document.getElementById('abc').id);
+
+  t.innerHTML = '<span>over</span><p>9000!</p>';
+  testing.expectEqual(2, t.content.childNodes.length);
+  testing.expectEqual('SPAN', t.content.childNodes[0].tagName);
+  testing.expectEqual('over', t.content.childNodes[0].innerHTML);
+  testing.expectEqual('P', t.content.childNodes[1].tagName);
+  testing.expectEqual('9000!', t.content.childNodes[1].innerHTML);
+</script>
+
+<template id="hello"><p>hello, world</p></template>
+
+<script id=template_parsing>
+  const tt = document.getElementById('hello');
+  testing.expectEqual('<p>hello, world</p>', tt.innerHTML);
+
+  // > The Node.childNodes property of the <template> element is always empty
+  // https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/template#usage_notes
+  testing.expectEqual(0, tt.childNodes.length);
+
+  let out = document.createElement('div');
+  out.appendChild(tt.content.cloneNode(true));
+
+  testing.expectEqual('<p>hello, world</p>', out.innerHTML);
+</script>
diff --git a/src/browser/tests/legacy/polyfill/webcomponents.html b/src/browser/tests/legacy/polyfill/webcomponents.html
new file mode 100644
index 00000000..5854bc82
--- /dev/null
+++ b/src/browser/tests/legacy/polyfill/webcomponents.html
@@ -0,0 +1,23 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<div id=main></div>
+
+<script id=webcomponents>
+  class LightPanda extends HTMLElement {
+    constructor() {
+      super();
+    }
+    connectedCallback() {
+      this.append('connected');
+    }
+  }
+
+  window.customElements.define("lightpanda-test", LightPanda);
+  const main = document.getElementById('main');
+  main.appendChild(document.createElement('lightpanda-test'));
+
+  testing.expectEqual('<lightpanda-test>connected</lightpanda-test>', main.innerHTML)
+  testing.expectEqual('[object DataSet]', document.createElement('lightpanda-test').dataset.toString());
+  testing.expectEqual('[object DataSet]', document.createElement('lightpanda-test.x').dataset.toString());
+</script>
diff --git a/src/browser/tests/legacy/storage/local_storage.html b/src/browser/tests/legacy/storage/local_storage.html
new file mode 100644
index 00000000..4ad0b14f
--- /dev/null
+++ b/src/browser/tests/legacy/storage/local_storage.html
@@ -0,0 +1,29 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=localstorage>
+  testing.expectEqual(0, localStorage.length);
+  testing.expectEqual(null, localStorage.getItem('foo'));
+  testing.expectEqual(null, localStorage.key(0));
+
+  localStorage.setItem('foo', 'bar');
+  testing.expectEqual(1, localStorage.length)
+  testing.expectEqual('bar', localStorage.getItem('foo'));
+  testing.expectEqual('bar', localStorage.key(0));
+  testing.expectEqual(null, localStorage.key(1));
+
+  localStorage.removeItem('foo');
+  testing.expectEqual(0, localStorage.length)
+  testing.expectEqual(null, localStorage.getItem('foo'));
+
+  localStorage['foo'] = 'bar';
+  testing.expectEqual(1, localStorage.length);
+  testing.expectEqual('bar', localStorage['foo']);
+
+  localStorage.setItem('a', '1');
+  localStorage.setItem('b', '2');
+  localStorage.setItem('c', '3');
+  testing.expectEqual(4, localStorage.length)
+  localStorage.clear();
+  testing.expectEqual(0, localStorage.length)
+</script>
diff --git a/src/browser/tests/legacy/streams/readable_stream.html b/src/browser/tests/legacy/streams/readable_stream.html
new file mode 100644
index 00000000..a8339cc5
--- /dev/null
+++ b/src/browser/tests/legacy/streams/readable_stream.html
@@ -0,0 +1,134 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<script id=readable_stream>
+  const stream = new ReadableStream({
+    start(controller) {
+      controller.enqueue("hello");
+      controller.enqueue("world");
+      controller.close();
+    }
+  });
+
+  const reader = stream.getReader();
+
+  testing.async(reader.read(), (data) => {
+    testing.expectEqual("hello", data.value);
+    testing.expectEqual(false, data.done);
+  });
+</script>
+
+<script id=readable_stream_binary>
+  const input = new TextEncoder().encode('over 9000!');
+  const binStream = new ReadableStream({
+    start(controller) {
+      controller.enqueue(input);
+      controller.enqueue("world");
+      controller.close();
+    }
+  });
+
+  testing.async(binStream.getReader().read(), (data) => {
+    testing.expectEqual(input, data.value);
+    testing.expectEqual(false, data.done);
+  });
+</script>
+
+<script id=readable_stream_close>
+  var closeResult;
+
+  const stream1 = new ReadableStream({
+    start(controller) {
+      controller.enqueue("first");
+      controller.enqueue("second");
+      controller.close();
+    }
+  });
+
+  const reader1 = stream1.getReader();
+
+  testing.async(reader1.read(), (data) => {
+    testing.expectEqual("first", data.value);
+    testing.expectEqual(false, data.done);
+  });
+
+  testing.async(reader1.read(), (data) => {
+    testing.expectEqual("second", data.value);
+    testing.expectEqual(false, data.done);
+  });
+
+  testing.async(reader1.read(), (data) => {
+    testing.expectEqual(undefined, data.value);
+    testing.expectEqual(true, data.done);
+  });
+</script>
+
+<script id=readable_stream_cancel>
+  var readResult;
+  var cancelResult;
+  var closeResult;
+
+  const stream2 = new ReadableStream({
+    start(controller) {
+      controller.enqueue("data1");
+      controller.enqueue("data2");
+      controller.enqueue("data3");
+    },
+    cancel(reason) {
+      closeResult = `Stream cancelled: ${reason}`;
+    }
+  });
+
+  const reader2 = stream2.getReader();
+
+  testing.async(reader2.read(), (data) => {
+    testing.expectEqual("data1", data.value);
+    testing.expectEqual(false, data.done);
+  });
+
+  testing.async(reader2.cancel("user requested"), (result) => {
+    testing.expectEqual(undefined, result);
+    testing.expectEqual("Stream cancelled: user requested", closeResult);
+  });
+</script>
+
+<script id=readable_stream_cancel_no_reason>
+  var closeResult2;
+
+  const stream3 = new ReadableStream({
+    start(controller) {
+      controller.enqueue("test");
+    },
+    cancel(reason) {
+      closeResult2 = reason === undefined ? "no reason" : reason;
+    }
+  });
+
+  const reader3 = stream3.getReader();
+
+  testing.async(reader3.cancel(), (result) => {
+    testing.expectEqual(undefined, result);
+    testing.expectEqual("no reason", closeResult2);
+  });
+</script>
+
+<script id=readable_stream_read_after_cancel>
+  var readAfterCancelResult;
+
+  const stream4 = new ReadableStream({
+    start(controller) {
+      controller.enqueue("before_cancel");
+    },
+  });
+
+  const reader4 = stream4.getReader();
+
+  testing.async(reader4.cancel("test cancel"), (cancelResult) => {
+    testing.expectEqual(undefined, cancelResult);
+  });
+
+  testing.async(reader4.read(), (data) => {
+    testing.expectEqual(undefined, data.value);
+    testing.expectEqual(true, data.done);
+  });
+</script>
diff --git a/src/browser/tests/legacy/testing.js b/src/browser/tests/legacy/testing.js
new file mode 100644
index 00000000..891d9cc2
--- /dev/null
+++ b/src/browser/tests/legacy/testing.js
@@ -0,0 +1,206 @@
+// Note: this code tries to make sure that we don't fail to execute a <script>
+// block without reporting an error. In other words, if the test passes, you
+// should be confident that the code actually ran.
+// We do a couple things to ensure this.
+// 1 - We make sure that ever script with an id has at least 1 assertion called
+// 2 - We add an onerror handler to every script and, on error, fail.
+//
+// This is pretty straightforward, with the only complexity coming from "eventually"
+// assertions, which are assertions we lazily check in `getStatus()`. We
+// do this because, by the time `getStatus()`, `page.wait()` will have been called
+// and any timer (setTimeout, requestAnimation, MutationObserver, etc...) will
+// have been evaluated. Test which use/test these behavior will use `eventually`.
+(() => {
+  function expectEqual(expected, actual) {
+    _recordExecution();
+    if (_equal(expected, actual)) {
+      return;
+    }
+    testing._status = 'fail';
+    let msg = `expected: ${JSON.stringify(expected)}, got: ${JSON.stringify(actual)}`;
+
+    console.warn(
+      `id: ${testing._captured?.script_id || document.currentScript.id}`,
+      `msg: ${msg}`,
+      `stack: ${testing._captured?.stack || new Error().stack}`,
+    );
+  }
+
+  function expectError(expected, fn) {
+    withError((err) => {
+      expectEqual(expected, err.toString());
+    }, fn);
+  }
+
+  function withError(cb, fn) {
+    try{
+      fn();
+    } catch (err) {
+      cb(err);
+      return;
+    }
+    expectEqual('an error', null);
+  }
+
+  function skip() {
+    _recordExecution();
+  }
+
+  // Should only be called by the test runner
+  function assertOk() {
+    // if we're already in a fail state, return fail, nothing can recover this
+    if (testing._status === 'fail') {
+      throw new Error('Failed');
+    }
+
+    // run any eventually's that we've captured
+    for (const ev of testing._eventually) {
+      testing._captured = ev[1];
+      ev[0]();
+      testing._captured = null;
+    }
+
+    // Again, if we're in a fail state, we can immediately fail
+    if (testing._status === 'fail') {
+      throw new Error('Failed');
+    }
+
+    // make sure that any <script id=xyz></script> tags we have have had at least
+    // 1 assertion. This helps ensure that if a script tag fails to execute,
+    // we'll report an error, even if no assertions failed.
+    const scripts = document.getElementsByTagName('script');
+    for (script of scripts) {
+      const id = script.id;
+      if (!id) {
+        continue;
+      }
+
+      if (!testing._executed_scripts.has(id)) {
+        console.warn(`Failed to execute any expectations for <script id="${id}">...</script>`);
+      	throw new Error('Failed');
+      }
+    }
+
+    if (testing._status != 'ok') {
+      throw new Error(testing._status);
+    }
+  }
+
+  // Set expectations to happen at some point in the future. Necessary for
+  // testing callbacks which will only be executed after page.wait is called.
+  function eventually(fn) {
+    // capture the current state (script id, stack) so that, when we do run this
+    // we can display more meaningful details on failure.
+    testing._eventually.push([fn, {
+      script_id: document.currentScript.id,
+      stack: new Error().stack,
+    }]);
+
+    _registerErrorCallback();
+  }
+
+  async function async(promise, cb) {
+    const script_id = document.currentScript ? document.currentScript.id : '<script id is unavailable in browsers>';
+    const stack = new Error().stack;
+    this._captured = {script_id: script_id, stack: stack};
+    const value = await promise;
+    // reset it, because await promise could change it.
+    this._captured = {script_id: script_id, stack: stack};
+    cb(value);
+    this._captured = null;
+  }
+
+  function _recordExecution() {
+    if (testing._status === 'fail') {
+      return;
+    }
+    testing._status = 'ok';
+
+    if (testing._captured || document.currentScript) {
+    	const script_id = testing._captured?.script_id || document.currentScript.id;
+    	testing._executed_scripts.add(script_id);
+	    _registerErrorCallback();
+    }
+  }
+
+  // We want to attach an onError callback to each <script>, so that we can
+  // properly fail it.
+  function _registerErrorCallback() {
+    const script = document.currentScript;
+    if (!script) {
+      // can be null if we're executing an eventually assertion, but that's ok
+      // because the errorCallback would have been registered for this script
+      // already
+      return;
+    }
+
+    if (script.onerror) {
+      // already registered
+      return;
+    }
+
+    script.onerror = function(err, b) {
+      testing._status = 'fail';
+      console.warn(
+        `id: ${script.id}`,
+        `msg: There was an error executing the <script id=${script.id}>...</script>.\n      There should be a eval error printed above this.`,
+      );
+    }
+  }
+
+  function _equal(a, b) {
+    if (a === b) {
+      return true;
+    }
+    if (a === null || b === null) {
+      return false;
+    }
+    if (typeof a !== 'object' || typeof b !== 'object') {
+      return false;
+    }
+
+    if (Object.keys(a).length != Object.keys(b).length) {
+      return false;
+    }
+
+    for (property in a) {
+      if (b.hasOwnProperty(property) === false) {
+        return false;
+      }
+      if (_equal(a[property], b[property]) === false) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+  window.testing = {
+    _status: 'empty',
+    _eventually: [],
+    _executed_scripts: new Set(),
+    _captured: null,
+    skip: skip,
+    async: async,
+    assertOk: assertOk,
+    eventually: eventually,
+    expectEqual: expectEqual,
+    expectError: expectError,
+    withError: withError,
+  };
+
+  // Helper, so you can do $(sel) in a test
+  window.$ = function(sel) {
+    return document.querySelector(sel);
+  }
+
+  // Helper, so you can do $$(sel) in a test
+  window.$$ = function(sel) {
+    return document.querySelectorAll(sel);
+  }
+
+  if (!console.lp) {
+    // make this work in the browser
+    console.lp = console.log;
+  }
+})();
diff --git a/src/browser/tests/legacy/url/url.html b/src/browser/tests/legacy/url/url.html
new file mode 100644
index 00000000..ef770e46
--- /dev/null
+++ b/src/browser/tests/legacy/url/url.html
@@ -0,0 +1,109 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=url>
+  var url = new URL('https://foo.bar/path?query#fragment');
+  testing.expectEqual("https://foo.bar", url.origin);
+  testing.expectEqual("https://foo.bar/path?query#fragment", url.href);
+  testing.expectEqual("https:", url.protocol);
+  testing.expectEqual("", url.username);
+  testing.expectEqual("", url.password);
+  testing.expectEqual("foo.bar", url.host);
+  testing.expectEqual("foo.bar", url.hostname);
+  testing.expectEqual("", url.port);
+  testing.expectEqual("/path", url.pathname);
+  testing.expectEqual("?query", url.search);
+  testing.expectEqual("#fragment", url.hash);
+  testing.expectEqual("", url.searchParams.get('query'));
+
+  url.search = 'hello=world';
+  testing.expectEqual(1, url.searchParams.size);
+  testing.expectEqual("world", url.searchParams.get('hello'));
+
+  url.search = '?over=9000';
+  testing.expectEqual(1, url.searchParams.size);
+  testing.expectEqual("9000", url.searchParams.get('over'));
+
+  url.search = '';
+  testing.expectEqual(0, url.searchParams.size);
+
+  const url2 = new URL(url);
+  testing.expectEqual("https://foo.bar/path#fragment", url2.href);
+</script>
+
+<script id="constructor">
+  testing.expectError("TypeError: invalid argument", () => {
+    new URL(document.createElement('a'));
+  });
+
+  let a = document.createElement('a');
+  a.href = 'https://www.lightpanda.io/over?9000=!!';
+  const url3 = new URL(a);
+  testing.expectEqual("https://www.lightpanda.io/over?9000=%21%21", url3.href);
+ </script>
+
+<script id=searchParams>
+  url = new URL('https://foo.bar/path?a=~&b=%7E#fragment');
+  testing.expectEqual("~", url.searchParams.get('a'));
+  testing.expectEqual("~", url.searchParams.get('b'));
+
+  url.searchParams.append('c', 'foo');
+  testing.expectEqual("foo", url.searchParams.get('c'));
+  testing.expectEqual(1, url.searchParams.getAll('c').length);
+  testing.expectEqual("foo", url.searchParams.getAll('c')[0]);
+  testing.expectEqual(3, url.searchParams.size);
+
+  // search is dynamic
+  testing.expectEqual("?a=~&b=~&c=foo", url.search);
+
+  // href is dynamic
+  testing.expectEqual("https://foo.bar/path?a=~&b=~&c=foo#fragment", url.href);
+
+  url.searchParams.delete('c', 'foo');
+  testing.expectEqual(null, url.searchParams.get('c'));
+  url.searchParams.delete('a');
+  testing.expectEqual(null, url.searchParams.get('a'));
+</script>
+
+<script id=searchParamsSetHref>
+  url = new URL("https://foo.bar");
+  const searchParams = url.searchParams;
+
+  // SearchParams should be empty.
+  testing.expectEqual(0, searchParams.size);
+
+  url.href = "https://lightpanda.io?over=9000&light=panda";
+  // It won't hurt to check href and host too.
+  testing.expectEqual("https://lightpanda.io/?over=9000&light=panda", url.href);
+  testing.expectEqual("lightpanda.io", url.host);
+  // SearchParams should be updated too when URL is set.
+  testing.expectEqual(2, searchParams.size);
+  testing.expectEqual("9000", searchParams.get("over"));
+  testing.expectEqual("panda", searchParams.get("light"));
+</script>
+
+<script id=base>
+  url = new URL('over?9000', 'https://lightpanda.io');
+  testing.expectEqual("https://lightpanda.io/over?9000", url.href);
+</script>
+
+<script id="svelkit">
+  let sk = new URL('sveltekit-internal://');
+  testing.expectEqual("sveltekit-internal:", sk.protocol);
+  testing.expectEqual("", sk.host);
+  testing.expectEqual("", sk.hostname);
+  testing.expectEqual("sveltekit-internal://", sk.href);
+</script>
+
+<script id=invalidUrl>
+  testing.expectError("Error: Invalid", () => {
+    _ = new URL("://foo.bar/path?query#fragment");
+  });
+</script>
+
+<script id=URL.canParse>
+  testing.expectEqual(true, URL.canParse("https://lightpanda.io"));
+  testing.expectEqual(false, URL.canParse("://lightpanda.io"));
+
+  testing.expectEqual(true, URL.canParse("/home", "https://lightpanda.io"));
+  testing.expectEqual(false, URL.canParse("lightpanda.io", "https"));
+</script>
diff --git a/src/browser/tests/legacy/url/url_search_params.html b/src/browser/tests/legacy/url/url_search_params.html
new file mode 100644
index 00000000..03f22bcd
--- /dev/null
+++ b/src/browser/tests/legacy/url/url_search_params.html
@@ -0,0 +1,94 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=url_search_params>
+  let usp = new URLSearchParams();
+  usp.get('a')
+  testing.expectEqual(false, usp.has('a'));
+  testing.expectEqual([], usp.getAll('a'));
+  usp.delete('a');
+
+  usp.set('a', 1);
+  testing.expectEqual(true, usp.has('a'));
+  testing.expectEqual("1", usp.get('a'));
+  testing.expectEqual(["1"], usp.getAll('a'));
+
+  usp.append('a', 2);
+  testing.expectEqual(true, usp.has('a'));
+  testing.expectEqual("1", usp.get('a'));
+  testing.expectEqual(['1','2'], usp.getAll('a'));
+
+  usp.append('b', '3');
+  testing.expectEqual(true, usp.has('a'));
+  testing.expectEqual("1", usp.get('a'));
+  testing.expectEqual(['1','2'], usp.getAll('a'));
+  testing.expectEqual(true, usp.has('b'));
+  testing.expectEqual("3", usp.get('b'));
+  testing.expectEqual(['3'], usp.getAll('b'));
+
+  let acc = [];
+  for (const key of usp.keys()) { acc.push(key) };
+  testing.expectEqual(['a', 'a', 'b'], acc);
+
+  acc = [];
+  for (const value of usp.values()) { acc.push(value) };
+  testing.expectEqual(['1', '2', '3'], acc);
+
+  acc = [];
+  for (const entry of usp.entries()) { acc.push(entry) };
+  testing.expectEqual([['a', '1'], ['a', '2'], ['b', '3']], acc);
+
+  acc = [];
+  for (const entry of usp) { acc.push(entry) };
+  testing.expectEqual([['a', '1'], ['a', '2'], ['b', '3']], acc);
+
+  usp.delete('a');
+  testing.expectEqual(false, usp.has('a'));
+  testing.expectEqual(true, usp.has('b'));
+
+  acc = [];
+  for (const key of usp.keys()) { acc.push(key) };
+  testing.expectEqual(['b'], acc);
+
+  acc = [];
+  for (const value of usp.values()) { acc.push(value) };
+  testing.expectEqual(['3'], acc);
+
+  acc = [];
+  for (const entry of usp.entries()) { acc.push(entry) };
+  testing.expectEqual([['b', '3']], acc);
+
+  acc = [];
+  for (const entry of usp) { acc.push(entry) };
+  testing.expectEqual([['b', '3']], acc);
+</script>
+
+<script id=parsed>
+  usp = new URLSearchParams('?hello');
+  testing.expectEqual('', usp.get('hello'));
+
+  usp = new URLSearchParams('?abc=');
+  testing.expectEqual('', usp.get('abc'));
+
+  usp = new URLSearchParams('?abc=123&');
+  testing.expectEqual('123', usp.get('abc'));
+  testing.expectEqual(1, usp.size);
+
+  var fd = new FormData();
+  fd.append('a', '1');
+  fd.append('a', '2');
+  fd.append('b', '3');
+  ups = new URLSearchParams(fd);
+
+  testing.expectEqual(3, ups.size);
+  testing.expectEqual(['1', '2'], ups.getAll('a'));
+
+  testing.expectEqual(['3'], ups.getAll('b'));
+
+  fd.delete('a'); // the two aren't linked, it created a copy
+  testing.expectEqual(3, ups.size);
+
+  ups = new URLSearchParams({over: 9000, spice: 'flow'});
+  testing.expectEqual(2, ups.size);
+  testing.expectEqual(['9000'], ups.getAll('over'));
+  testing.expectEqual(['flow'], ups.getAll('spice'));
+</script>
diff --git a/src/browser/tests/legacy/window/frames.html b/src/browser/tests/legacy/window/frames.html
new file mode 100644
index 00000000..fc4b7abc
--- /dev/null
+++ b/src/browser/tests/legacy/window/frames.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<body>
+ <iframe src="https://httpbin.io/html" title="iframea"></iframe>
+ <iframe src="https://httpbin.io/html" title="iframeb"></iframe>
+</body>
+
+<script id=frames>
+  testing.expectEqual(2, frames.length);
+  testing.expectEqual(undefined, frames[3])
+  testing.expectError('Error: TODO', () => { frames[1] });
+</script>
diff --git a/src/browser/tests/legacy/window/window.html b/src/browser/tests/legacy/window/window.html
new file mode 100644
index 00000000..aac91171
--- /dev/null
+++ b/src/browser/tests/legacy/window/window.html
@@ -0,0 +1,167 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<body style=height:4000px;width:4000px></body>
+<script id=aliases>
+  testing.expectEqual(window, window.self);
+  testing.expectEqual(window, window.parent);
+  testing.expectEqual(window, window.top);
+  testing.expectEqual(window, window.frames);
+  testing.expectEqual(0, window.frames.length);
+</script>
+
+<script id=request_animation>
+  let start = 0;
+  function step(timestamp) {
+    start = timestamp;
+  }
+  requestAnimationFrame(step);
+  testing.eventually(() => testing.expectEqual(true, start > 0));
+
+  let request_id = requestAnimationFrame(() => {
+    start = 0;
+  });
+  cancelAnimationFrame(request_id);
+  testing.eventually(() => testing.expectEqual(true, start > 0));
+</script>
+
+<script id=dimensions>
+  testing.expectEqual(5, innerHeight);
+  // Width is 5 even if there are no elements
+  testing.expectEqual(5, innerWidth);
+
+  let div1 = document.createElement('div');
+  document.body.appendChild(div1);
+  div1.getClientRects()
+
+  let div2 = document.createElement('div');
+  document.body.appendChild(div2);
+  div2.getClientRects();
+
+  testing.expectEqual(5, innerHeight);
+  testing.expectEqual(10, innerWidth);
+</script>
+
+<script id=setTimeout>
+  let longCall = false;
+  window.setTimeout(() => {longCall = true}, 5001);
+  testing.eventually(() => testing.expectEqual(false, longCall));
+
+  let wst1 = 0;
+  window.setTimeout(() => {wst1 += 1}, 1);
+  testing.eventually(() => testing.expectEqual(1, wst1));
+
+  let wst2 = 1;
+  window.setTimeout((a, b) => {wst2 = a + b}, 1, 2, 3);
+  testing.eventually(() => testing.expectEqual(5, wst2));
+</script>
+
+<script id=eventTarget>
+  let called = false;
+
+  window.addEventListener("ready", (e) => {
+    called = (e.currentTarget == window);
+  }, {capture: false, once: false});
+
+  const evt = new Event("ready", { bubbles: true, cancelable: false });
+  window.dispatchEvent(evt);
+  testing.expectEqual(true, called);
+</script>
+
+<script id=btoa_atob>
+  const b64 = btoa('https://ziglang.org/documentation/master/std/#std.base64.Base64Decoder')
+  testing.expectEqual('aHR0cHM6Ly96aWdsYW5nLm9yZy9kb2N1bWVudGF0aW9uL21hc3Rlci9zdGQvI3N0ZC5iYXNlNjQuQmFzZTY0RGVjb2Rlcg==', b64);
+
+  const str = atob(b64)
+  testing.expectEqual('https://ziglang.org/documentation/master/std/#std.base64.Base64Decoder', str);
+
+  testing.expectError('Error: InvalidCharacterError', () => {
+    atob('b');
+  });
+</script>
+
+<script id=scroll>
+  let scroll = false;
+  let scrollend = false
+
+  window.addEventListener('scroll', () => {scroll = true});
+  document.addEventListener('scrollend', () => {scrollend = true});
+  window.scrollTo(0, 0);
+  testing.expectEqual(0, scrollX);
+  testing.expectEqual(0, pageXOffset);
+  testing.expectEqual(0, scrollY);
+  testing.expectEqual(0, pageYOffset);
+
+  testing.expectEqual(true, scroll);
+  testing.expectEqual(true, scrollend);
+
+  window.scrollTo(10, 20);
+  testing.expectEqual(10, scrollX);
+  testing.expectEqual(10, pageXOffset);
+  testing.expectEqual(20, scrollY);
+  testing.expectEqual(20, pageYOffset);
+
+  window.scrollTo(-10, -20);
+  testing.expectEqual(0, scrollX);
+  testing.expectEqual(0, pageXOffset);
+  testing.expectEqual(0, scrollY);
+  testing.expectEqual(0, pageYOffset);
+
+  window.scrollTo({top: 30, left: 40});
+  testing.expectEqual(40, scrollX);
+  testing.expectEqual(40, pageXOffset);
+  testing.expectEqual(30, scrollY);
+  testing.expectEqual(30, pageYOffset);
+
+  window.scrollTo({top: -30, left: -40});
+  testing.expectEqual(0, scrollX);
+  testing.expectEqual(0, pageXOffset);
+  testing.expectEqual(0, scrollY);
+  testing.expectEqual(0, pageYOffset);
+</script>
+
+<script id=queueMicroTask>
+  var qm = false;
+  window.queueMicrotask(() => {qm = true });
+  testing.eventually(() => testing.expectEqual(true, qm));
+</script>
+
+<script id=DOMContentLoaded>
+  let dcl = false;
+  window.queueMicrotask(() => {qm = true });
+  window.addEventListener('DOMContentLoaded', (e) => {
+    dcl = e.target == document;
+  });
+  testing.eventually(() => testing.expectEqual(true, dcl));
+</script>
+
+<script id=window.onload>
+  let isWindowTarget = false;
+
+  const callback = (e) => isWindowTarget = e.target === window;
+  // Callback is not set yet.
+  testing.expectEqual(null, window.onload);
+  // Setting an object.
+  window.onload = {};
+  testing.expectEqual(null, window.onload);
+  // Callback is set.
+  window.onload = callback;
+  testing.expectEqual(callback, window.onload);
+
+  testing.eventually(() => testing.expectEqual(true, isWindowTarget));
+</script>
+
+<script id=reportError>
+  let errorEventFired = false;
+  let capturedError = null;
+
+  window.addEventListener('error', (e) => {
+    errorEventFired = true;
+    capturedError = e.error;
+  });
+
+  const testError = new Error('Test error message');
+  window.reportError(testError);
+
+  testing.expectEqual(true, errorEventFired);
+  testing.expectEqual(testError, capturedError);
+</script>
diff --git a/src/browser/tests/legacy/xhr/form_data.html b/src/browser/tests/legacy/xhr/form_data.html
new file mode 100644
index 00000000..94bf8a27
--- /dev/null
+++ b/src/browser/tests/legacy/xhr/form_data.html
@@ -0,0 +1,130 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=formData>
+  let f = new FormData();
+  testing.expectEqual(null, f.get('a'));
+  testing.expectEqual(false, f.has('a'));
+  testing.expectEqual([], f.getAll('a'));
+  testing.expectEqual(undefined, f.delete('a'));
+
+  f.set('a', 1);
+  testing.expectEqual(true, f.has('a'));
+  testing.expectEqual('1', f.get('a'));
+  testing.expectEqual(['1'], f.getAll('a'));
+
+  f.append('a', 2);
+  testing.expectEqual(true, f.has('a'));
+  testing.expectEqual('1', f.get('a'));
+  testing.expectEqual(['1', '2'], f.getAll('a'));
+
+  f.append('b', '3');
+  testing.expectEqual(true, f.has('a'));
+  testing.expectEqual('1', f.get('a'));
+  testing.expectEqual(['1', '2'], f.getAll('a'));
+  testing.expectEqual(true, f.has('b'));
+  testing.expectEqual('3', f.get('b'));
+  testing.expectEqual(['3'], f.getAll('b'));
+
+  let acc = [];
+  for (const key of f.keys()) { acc.push(key) }
+  testing.expectEqual(['a', 'a', 'b'], acc);
+
+  acc = [];
+  for (const value of f.values()) { acc.push(value) }
+  testing.expectEqual(['1', '2', '3'], acc);
+
+  acc = [];
+  for (const entry of f.entries()) { acc.push(entry) }
+  testing.expectEqual([['a', '1'], ['a', '2'], ['b', '3']], acc);
+
+  acc = [];
+  for (const entry of f) { acc.push(entry) };
+  testing.expectEqual([['a', '1'], ['a', '2'], ['b', '3']], acc);
+
+  f.delete('a');
+  testing.expectEqual(false, f.has('a'));
+  testing.expectEqual(true, f.has('b'));
+
+  acc = [];
+  for (const key of f.keys()) { acc.push(key) }
+  testing.expectEqual(['b'], acc);
+
+  acc = [];
+  for (const value of f.values()) { acc.push(value) }
+  testing.expectEqual(['3'], acc);
+
+  acc = [];
+  for (const entry of f.entries()) { acc.push(entry) }
+  testing.expectEqual([['b', '3']], acc);
+
+  acc = [];
+  for (const entry of f) { acc.push(entry) }
+  testing.expectEqual([['b', '3']], acc);
+</script>
+
+<script id=serialize>
+  let form1 = $('#form1');
+  let submit1 = $('#s1');
+
+  let input = document.createElement('input');
+  input.name = 'dyn';
+  input.value = 'dyn-v';
+  form1.appendChild(input);
+  let f2 = new FormData(form1, submit1);
+
+  acc = [];
+  for (const entry of f2) {
+    acc.push(entry);
+  };
+
+  testing.expectEqual(['txt-1', 'txt-1-v'], acc[0]);
+  testing.expectEqual(['txt-2', 'txt-~-v'], acc[1]);
+  testing.expectEqual(['chk-3', 'chk-3-vb'], acc[2]);
+  testing.expectEqual(['chk-3', 'chk-3-vc'], acc[3]);
+  testing.expectEqual(['rdi-1', 'rdi-1-vc'], acc[4]);
+  testing.expectEqual(['ta-1', ' ta-1-v'], acc[5]);
+  testing.expectEqual(['ta', ''], acc[6]);
+  testing.expectEqual(['h1', 'h1-v'], acc[7]);
+  testing.expectEqual(['sel-1', 'blue'], acc[8]);
+  testing.expectEqual(['sel-2', 'sel-2-v'], acc[9]);
+  testing.expectEqual(['mlt-2', 'water'], acc[10]);
+  testing.expectEqual(['mlt-2', 'tea'], acc[11]);
+  testing.expectEqual(['s1', 's1-v'], acc[12]);
+  testing.expectEqual(['dyn', 'dyn-v'], acc[13]);
+</script>
+
+<form id="form1">
+  <input id="has_no_name" value="nope1">
+  <input id="is_disabled" disabled value="nope2">
+
+  <input name="txt-1" value="txt-1-v">
+  <input name="txt-2" value="txt-~-v" type=password>
+
+  <input name="chk-3" value="chk-3-va" type=checkbox>
+  <input name="chk-3" value="chk-3-vb" type=checkbox checked>
+  <input name="chk-3" value="chk-3-vc" type=checkbox checked>
+  <input name="chk-4" value="chk-4-va" type=checkbox>
+  <input name="chk-4" value="chk-4-va" type=checkbox>
+
+  <input name="rdi-1" value="rdi-1-va" type=radio>
+  <input name="rdi-1" value="rdi-1-vb" type=radio>
+  <input name="rdi-1" value="rdi-1-vc" type=radio checked>
+  <input name="rdi-2" value="rdi-2-va" type=radio>
+  <input name="rdi-2" value="rdi-2-vb" type=radio>
+
+  <textarea name="ta-1"> ta-1-v</textarea>
+  <textarea name="ta"></textarea>
+
+  <input type=hidden name=h1 value="h1-v">
+  <input type=hidden name=h2 value="h2-v" disabled=disabled>
+
+  <select name="sel-1"><option>blue<option>red</select>
+  <select name="sel-2"><option>blue<option value=sel-2-v selected>red</select>
+  <select name="sel-3"><option disabled>nope1<option>nope2</select>
+  <select name="mlt-1" multiple><option>water<option>tea</select>
+  <select name="mlt-2" multiple><option selected>water<option selected>tea<option>coffee</select>
+  <input type=submit id=s1 name=s1 value=s1-v>
+  <input type=submit name=s2 value=s2-v>
+  <input type=image name=i1 value=i1-v>
+</form>
+<input type=text name=abc value=123 form=form1>
diff --git a/src/browser/tests/legacy/xhr/progress_event.html b/src/browser/tests/legacy/xhr/progress_event.html
new file mode 100644
index 00000000..4b7f5df4
--- /dev/null
+++ b/src/browser/tests/legacy/xhr/progress_event.html
@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=progressEvent>
+  let pevt = new ProgressEvent('foo');
+  testing.expectEqual(0, pevt.loaded);
+
+  testing.expectEqual(true, pevt instanceof ProgressEvent);
+
+  var eevt = null;
+  function ccbk(event) {
+    eevt =  event;
+  }
+  document.addEventListener('foo', ccbk)
+  document.dispatchEvent(pevt);
+  testing.expectEqual('foo', eevt.type);
+  testing.expectEqual(true, eevt instanceof ProgressEvent);
+</script>
diff --git a/src/browser/tests/legacy/xhr/xhr.html b/src/browser/tests/legacy/xhr/xhr.html
new file mode 100644
index 00000000..13ab6216
--- /dev/null
+++ b/src/browser/tests/legacy/xhr/xhr.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+<script id=xhr type=module>
+  const req = new XMLHttpRequest();
+  const promise1 = new Promise((resolve) => {
+    function cbk(event) {
+      resolve(event)
+    }
+
+    req.onload = cbk;
+    testing.expectEqual(cbk, req.onload);
+    req.onload = cbk;
+
+    req.open('GET', 'http://127.0.0.1:9582/xhr');
+    testing.expectEqual(0, req.status);
+    testing.expectEqual('', req.statusText);
+    testing.expectEqual('', req.getAllResponseHeaders());
+    testing.expectEqual(null, req.getResponseHeader('Content-Type'));
+    testing.expectEqual('', req.responseText);
+
+    req.send();
+  });
+
+  testing.async(promise1, (event) => {
+    testing.expectEqual('load', event.type);
+    testing.expectEqual(true, event.loaded > 0);
+    testing.expectEqual(true, event instanceof ProgressEvent);
+    testing.expectEqual(200, req.status);
+    testing.expectEqual('OK', req.statusText);
+    testing.expectEqual('text/html; charset=utf-8', req.getResponseHeader('Content-Type'));
+    testing.expectEqual('content-length: 100\r\nContent-Type: text/html; charset=utf-8\r\n', req.getAllResponseHeaders());
+    testing.expectEqual(100, req.responseText.length);
+    testing.expectEqual(req.responseText.length, req.response.length);
+    testing.expectEqual(true, req.responseXML instanceof Document);
+  });
+</script>
+
+<script id=xhr2 type=module>
+  const req2 = new XMLHttpRequest()
+  const promise2 = new Promise((resolve) => {
+    req2.onload = resolve;
+    req2.open('GET', 'http://127.0.0.1:9582/xhr')
+    req2.responseType = 'document';
+    req2.send()
+  });
+
+  testing.async(promise2, () => {
+    testing.expectEqual(200, req2.status);
+    testing.expectEqual('OK', req2.statusText);
+    testing.expectEqual(true, req2.response instanceof Document);
+    testing.expectEqual(true, req2.responseXML instanceof Document);
+  });
+</script>
+
+<script id=xhr3 type=module>
+  const req3 = new XMLHttpRequest()
+  const promise3 = new Promise((resolve) => {
+    req3.onload = resolve;
+    req3.open('GET', 'http://127.0.0.1:9582/xhr/json')
+    req3.responseType = 'json';
+    req3.send()
+  });
+
+  testing.async(promise3, () => {
+    testing.expectEqual(200, req3.status);
+    testing.expectEqual('OK', req3.statusText);
+    testing.expectEqual('9000!!!', req3.response.over);
+  });
+</script>
+
+<script id=xhr4 type=module>
+  const req4 = new XMLHttpRequest()
+  const promise4 = new Promise((resolve) => {
+    req4.onload = resolve;
+    req4.open('POST', 'http://127.0.0.1:9582/xhr')
+    req4.send('foo')
+  });
+
+  testing.async(promise4, () => {
+    testing.expectEqual(200, req4.status);
+    testing.expectEqual('OK', req4.statusText);
+    testing.expectEqual(true, req4.responseText.length > 64);
+  });
+</script>
+
+<script id=xhr5 type=module>
+  const promise5 = new Promise((resolve) => {
+    var state = [];
+    const req5 = new XMLHttpRequest();
+    req5.onreadystatechange = (e) => {
+      state.push(req5.readyState);
+      if (req5.readyState === XMLHttpRequest.DONE) {
+        resolve({states: state, target: e.currentTarget});
+      }
+    }
+
+    req5.open('GET', 'http://127.0.0.1:9582/xhr');
+    req5.send();
+  });
+
+  testing.async(promise5, (result) => {
+    const {states: states, target: target} = result;
+    testing.expectEqual(4, states.length)
+    testing.expectEqual(XMLHttpRequest.OPENED, readyStates[0]);
+    testing.expectEqual(XMLHttpRequest.HEADERS_RECEIVED, readyStates[1]);
+    testing.expectEqual(XMLHttpRequest.LOADING, readyStates[2]);
+    testing.expectEqual(XMLHttpRequest.DONE, readyStates[3]);
+    testing.expectEqual(req5, target);
+  })
+</script>
diff --git a/src/browser/tests/legacy/xmlserializer.html b/src/browser/tests/legacy/xmlserializer.html
new file mode 100644
index 00000000..0d3d4628
--- /dev/null
+++ b/src/browser/tests/legacy/xmlserializer.html
@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<script src="testing.js"></script>
+<p id="para"> And</p>
+<script id=xmlserializer>
+  const s = new XMLSerializer();
+  testing.expectEqual('<p id="para"> And</p>', s.serializeToString($('#para')));
+  testing.expectEqual('<!DOCTYPE html>', s.serializeToString(document.doctype));
+</script>
diff --git a/src/browser/webapi/DOMParser.zig b/src/browser/webapi/DOMParser.zig
index 35831295..051f004b 100644
--- a/src/browser/webapi/DOMParser.zig
+++ b/src/browser/webapi/DOMParser.zig
@@ -24,8 +24,6 @@ const Document = @import("Document.zig");
 const HTMLDocument = @import("HTMLDocument.zig");
 
 const DOMParser = @This();
-// @ZIGDOM support empty structs
-_: u8 = 0,
 
 pub fn init() DOMParser {
     return .{};
@@ -63,6 +61,7 @@ pub const JsApi = struct {
         pub const name = "DOMParser";
         pub const prototype_chain = bridge.prototypeChain();
         pub var class_id: bridge.ClassId = undefined;
+        pub const empty_with_no_proto = true;
     };
 
     pub const constructor = bridge.constructor(DOMParser.init, .{});
diff --git a/src/browser/webapi/NodeFilter.zig b/src/browser/webapi/NodeFilter.zig
index c9fab415..232355dc 100644
--- a/src/browser/webapi/NodeFilter.zig
+++ b/src/browser/webapi/NodeFilter.zig
@@ -85,6 +85,7 @@ pub const JsApi = struct {
         pub const name = "NodeFilter";
         pub const prototype_chain = bridge.prototypeChain();
         pub var class_id: bridge.ClassId = undefined;
+        pub const empty_with_no_proto = true;
     };
 
     pub const FILTER_ACCEPT = bridge.property(NodeFilter.FILTER_ACCEPT);
diff --git a/src/lightpanda.zig b/src/lightpanda.zig
index 57d27793..9c15f722 100644
--- a/src/lightpanda.zig
+++ b/src/lightpanda.zig
@@ -19,8 +19,12 @@
 const std = @import("std");
 pub const App = @import("App.zig");
 pub const Server = @import("Server.zig");
+pub const Page = @import("browser/Page.zig");
+pub const Browser = @import("browser/Browser.zig");
+pub const Session = @import("browser/Session.zig");
 
 pub const log = @import("log.zig");
+pub const js = @import("browser/js/js.zig");
 pub const dump = @import("browser/dump.zig");
 pub const build_config = @import("build_config");
 
@@ -32,7 +36,6 @@ pub const FetchOpts = struct {
     writer: ?*std.Io.Writer = null,
 };
 pub fn fetch(app: *App, url: [:0]const u8, opts: FetchOpts) !void {
-    const Browser = @import("browser/Browser.zig");
     var browser = try Browser.init(app);
     defer browser.deinit();
 
diff --git a/src/main_legacy_test.zig b/src/main_legacy_test.zig
new file mode 100644
index 00000000..4dc93e7e
--- /dev/null
+++ b/src/main_legacy_test.zig
@@ -0,0 +1,238 @@
+const std = @import("std");
+const lp = @import("lightpanda");
+
+const Allocator = std.mem.Allocator;
+
+// used in custom panic handler
+var current_test: ?[]const u8 = null;
+
+pub fn main() !void {
+    var gpa: std.heap.DebugAllocator(.{}) = .init;
+    defer _ = gpa.deinit();
+
+    const allocator = gpa.allocator();
+
+    var http_server = try TestHTTPServer.init();
+    defer http_server.deinit();
+
+    {
+        var wg: std.Thread.WaitGroup = .{};
+        wg.startMany(1);
+        var thrd = try std.Thread.spawn(.{}, TestHTTPServer.run, .{ &http_server, &wg });
+        thrd.detach();
+        wg.wait();
+    }
+    lp.log.opts.level = .warn;
+
+    var app = try lp.App.init(allocator, .{
+        .run_mode = .serve,
+        .tls_verify_host = false,
+        .user_agent = "User-Agent: Lightpanda/1.0 internal-tester",
+    });
+    defer app.deinit();
+
+    var test_arena = std.heap.ArenaAllocator.init(allocator);
+    defer test_arena.deinit();
+
+    var browser = try lp.Browser.init(app);
+    defer browser.deinit();
+
+    const session = try browser.newSession();
+
+    var dir = try std.fs.cwd().openDir("src/browser/tests/legacy/", .{ .iterate = true, .no_follow = true });
+    defer dir.close();
+    var walker = try dir.walk(allocator);
+    defer walker.deinit();
+    while (try walker.next()) |entry| {
+        _ = test_arena.reset(.retain_capacity);
+        if (entry.kind != .file) {
+            continue;
+        }
+
+        if (!std.mem.endsWith(u8, entry.basename, ".html")) {
+            continue;
+        }
+        std.debug.print("\n===={s}====\n", .{entry.path});
+        current_test = entry.path;
+        run(test_arena.allocator(), entry.path, session) catch |err| {
+            std.debug.print("Failure: {s} - {any}\n", .{ entry.path, err });
+        };
+    }
+}
+
+pub fn run(allocator: Allocator, file: []const u8, session: *lp.Session) !void {
+    const url = try std.fmt.allocPrintSentinel(allocator, "http://localhost:9589/{s}", .{file}, 0);
+
+    const page = try session.createPage();
+    defer session.removePage();
+
+    const js_context = page.js;
+    var try_catch: lp.js.TryCatch = undefined;
+    try_catch.init(js_context);
+    defer try_catch.deinit();
+
+    try page.navigate(url, .{});
+    session.fetchWait(2000);
+
+    page._session.browser.runMicrotasks();
+    page._session.browser.runMessageLoop();
+
+    js_context.eval("testing.assertOk()", "testing.assertOk()") catch |err| {
+        const msg = try_catch.err(allocator) catch @errorName(err) orelse "unknown";
+
+        std.debug.print("{s}: test failure\nError: {s}\n", .{ file, msg });
+        return err;
+    };
+}
+
+const TestHTTPServer = struct {
+    shutdown: bool,
+    dir: std.fs.Dir,
+    listener: ?std.net.Server,
+
+    pub fn init() !TestHTTPServer {
+        return .{
+            .dir = try std.fs.cwd().openDir("src/browser/tests/legacy/", .{}),
+            .shutdown = true,
+            .listener = null,
+        };
+    }
+
+    pub fn deinit(self: *TestHTTPServer) void {
+        self.shutdown = true;
+        if (self.listener) |*listener| {
+            listener.deinit();
+        }
+        self.dir.close();
+    }
+
+    pub fn run(self: *TestHTTPServer, wg: *std.Thread.WaitGroup) !void {
+        const address = try std.net.Address.parseIp("127.0.0.1", 9589);
+
+        self.listener = try address.listen(.{ .reuse_address = true });
+        var listener = &self.listener.?;
+
+        wg.finish();
+
+        while (true) {
+            const conn = listener.accept() catch |err| {
+                if (self.shutdown) {
+                    return;
+                }
+                return err;
+            };
+            const thrd = try std.Thread.spawn(.{}, handleConnection, .{ self, conn });
+            thrd.detach();
+        }
+    }
+
+    fn handleConnection(self: *TestHTTPServer, conn: std.net.Server.Connection) !void {
+        defer conn.stream.close();
+
+        var req_buf: [2048]u8 = undefined;
+        var conn_reader = conn.stream.reader(&req_buf);
+        var conn_writer = conn.stream.writer(&req_buf);
+
+        var http_server = std.http.Server.init(conn_reader.interface(), &conn_writer.interface);
+
+        while (true) {
+            var req = http_server.receiveHead() catch |err| switch (err) {
+                error.ReadFailed => continue,
+                error.HttpConnectionClosing => continue,
+                else => {
+                    std.debug.print("Test HTTP Server error: {}\n", .{err});
+                    return err;
+                },
+            };
+
+            self.handler(&req) catch |err| {
+                std.debug.print("test http error '{s}': {}\n", .{ req.head.target, err });
+                try req.respond("server error", .{ .status = .internal_server_error });
+                return;
+            };
+        }
+    }
+
+    fn handler(server: *TestHTTPServer, req: *std.http.Server.Request) !void {
+        const path = req.head.target;
+
+        // strip out leading '/' to make the path relative
+        const file = try server.dir.openFile(path[1..], .{});
+        defer file.close();
+
+        const stat = try file.stat();
+        var send_buffer: [4096]u8 = undefined;
+
+        var res = try req.respondStreaming(&send_buffer, .{
+            .content_length = stat.size,
+            .respond_options = .{
+                .extra_headers = &.{
+                    .{ .name = "content-type", .value = getContentType(path) },
+                },
+            },
+        });
+
+        var read_buffer: [4096]u8 = undefined;
+        var reader = file.reader(&read_buffer);
+        _ = try res.writer.sendFileAll(&reader, .unlimited);
+        try res.writer.flush();
+        try res.end();
+    }
+
+    pub fn sendFile(req: *std.http.Server.Request, file_path: []const u8) !void {
+        var file = std.fs.cwd().openFile(file_path, .{}) catch |err| switch (err) {
+            error.FileNotFound => return req.respond("server error", .{ .status = .not_found }),
+            else => return err,
+        };
+        defer file.close();
+
+        const stat = try file.stat();
+        var send_buffer: [4096]u8 = undefined;
+
+        var res = try req.respondStreaming(&send_buffer, .{
+            .content_length = stat.size,
+            .respond_options = .{
+                .extra_headers = &.{
+                    .{ .name = "content-type", .value = getContentType(file_path) },
+                },
+            },
+        });
+
+        var read_buffer: [4096]u8 = undefined;
+        var reader = file.reader(&read_buffer);
+        _ = try res.writer.sendFileAll(&reader, .unlimited);
+        try res.writer.flush();
+        try res.end();
+    }
+
+    fn getContentType(file_path: []const u8) []const u8 {
+        if (std.mem.endsWith(u8, file_path, ".js")) {
+            return "application/json";
+        }
+
+        if (std.mem.endsWith(u8, file_path, ".html")) {
+            return "text/html";
+        }
+
+        if (std.mem.endsWith(u8, file_path, ".htm")) {
+            return "text/html";
+        }
+
+        if (std.mem.endsWith(u8, file_path, ".xml")) {
+            // some wpt tests do this
+            return "text/xml";
+        }
+
+        std.debug.print("TestHTTPServer asked to serve an unknown file type: {s}\n", .{file_path});
+        return "text/html";
+    }
+};
+
+pub const panic = std.debug.FullPanic(struct {
+    pub fn panicFn(msg: []const u8, first_trace_addr: ?usize) noreturn {
+        if (current_test) |ct| {
+            std.debug.print("===panic running: {s}===\n", .{ct});
+        }
+        std.debug.defaultPanic(msg, first_trace_addr);
+    }
+}.panicFn);
diff --git a/tests/html/bug-html-parsing-4.html b/tests/html/bug-html-parsing-4.html
deleted file mode 100644
index 391ac0c7..00000000
--- a/tests/html/bug-html-parsing-4.html
+++ /dev/null
@@ -1,6 +0,0 @@
-<html
-	class="aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa">
-	<head>
-		<meta charset="UTF-8">
-	</head>
-</html>