From c9882e10a49de77b58e50789244dd9913d6648e1 Mon Sep 17 00:00:00 2001
From: Karl Seguin <k@openmymind.io>
Date: Thu, 4 Dec 2025 14:39:15 +0800
Subject: [PATCH] Properly handle insertion of DocumentFragment

Add various CData methods

XHR and Fetch request headers

Animation mocks
---
 src/browser/Page.zig                          |  18 +
 src/browser/js/Object.zig                     |   6 +-
 src/browser/js/bridge.zig                     |   1 +
 src/browser/tests/cdata/character_data.html   | 730 ++++++++++++++++++
 .../tests/document_fragment/insertion.html    | 238 ++++++
 src/browser/tests/net/request.html            |   6 +
 src/browser/webapi/CData.zig                  | 133 ++++
 src/browser/webapi/DOMException.zig           |   4 +
 src/browser/webapi/Element.zig                |  21 +-
 src/browser/webapi/KeyValueList.zig           |  31 +
 src/browser/webapi/Node.zig                   |   6 +-
 src/browser/webapi/Window.zig                 |   2 +-
 src/browser/webapi/animation/Animation.zig    |  49 ++
 src/browser/webapi/net/Fetch.zig              |  10 +-
 src/browser/webapi/net/Headers.zig            |  31 +-
 src/browser/webapi/net/Request.zig            |  14 +-
 src/browser/webapi/net/Response.zig           |   2 +-
 src/browser/webapi/net/URLSearchParams.zig    |  21 +-
 src/browser/webapi/net/XMLHttpRequest.zig     |  13 +-
 19 files changed, 1288 insertions(+), 48 deletions(-)
 create mode 100644 src/browser/tests/cdata/character_data.html
 create mode 100644 src/browser/tests/document_fragment/insertion.html
 create mode 100644 src/browser/webapi/animation/Animation.zig

diff --git a/src/browser/Page.zig b/src/browser/Page.zig
index 7f8ad2bc..6c94e453 100644
--- a/src/browser/Page.zig
+++ b/src/browser/Page.zig
@@ -1431,6 +1431,24 @@ pub fn appendAllChildren(self: *Page, parent: *Node, target: *Node) !void {
     }
 }
 
+pub fn insertAllChildrenBefore(self: *Page, fragment: *Node, target: *Node, ref_node: *Node) !void {
+    self.domChanged();
+    const dest_connected = target.isConnected();
+
+    var it = fragment.childrenIterator();
+    while (it.next()) |child| {
+        // Check if child was connected BEFORE removing it from fragment
+        const child_was_connected = child.isConnected();
+        self.removeNode(fragment, child, .{ .will_be_reconnected = dest_connected });
+        try self.insertNodeRelative(
+            target,
+            child,
+            .{ .before = ref_node },
+            .{ .child_already_connected = child_was_connected },
+        );
+    }
+}
+
 fn _appendNode(self: *Page, comptime from_parser: bool, parent: *Node, child: *Node, opts: InsertNodeOpts) !void {
     self._insertNodeRelative(from_parser, parent, child, .append, opts);
 }
diff --git a/src/browser/js/Object.zig b/src/browser/js/Object.zig
index 222f2b75..9ab35fe1 100644
--- a/src/browser/js/Object.zig
+++ b/src/browser/js/Object.zig
@@ -135,7 +135,7 @@ pub fn isNullOrUndefined(self: Object) bool {
     return self.js_obj.toValue().isNullOrUndefined();
 }
 
-pub fn nameIterator(self: Object, allocator: Allocator) NameIterator {
+pub fn nameIterator(self: Object) NameIterator {
     const context = self.context;
     const js_obj = self.js_obj;
 
@@ -145,7 +145,6 @@ pub fn nameIterator(self: Object, allocator: Allocator) NameIterator {
     return .{
         .count = count,
         .context = context,
-        .allocator = allocator,
         .js_obj = array.castTo(v8.Object),
     };
 }
@@ -158,7 +157,6 @@ pub const NameIterator = struct {
     count: u32,
     idx: u32 = 0,
     js_obj: v8.Object,
-    allocator: Allocator,
     context: *const Context,
 
     pub fn next(self: *NameIterator) !?[]const u8 {
@@ -170,6 +168,6 @@ pub const NameIterator = struct {
 
         const context = self.context;
         const js_val = try self.js_obj.getAtIndex(context.v8_context, idx);
-        return try context.valueToString(js_val, .{ .allocator = self.allocator });
+        return try context.valueToString(js_val, .{});
     }
 };
diff --git a/src/browser/js/bridge.zig b/src/browser/js/bridge.zig
index e20d9b7f..372d260a 100644
--- a/src/browser/js/bridge.zig
+++ b/src/browser/js/bridge.zig
@@ -568,6 +568,7 @@ pub const JsApis = flattenTypes(&.{
     @import("../webapi/media/MediaError.zig"),
     @import("../webapi/media/TextTrackCue.zig"),
     @import("../webapi/media/VTTCue.zig"),
+    @import("../webapi/animation/Animation.zig"),
     @import("../webapi/EventTarget.zig"),
     @import("../webapi/Location.zig"),
     @import("../webapi/Navigator.zig"),
diff --git a/src/browser/tests/cdata/character_data.html b/src/browser/tests/cdata/character_data.html
new file mode 100644
index 00000000..85513b00
--- /dev/null
+++ b/src/browser/tests/cdata/character_data.html
@@ -0,0 +1,730 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<div id="container"></div>
+
+<script id="lengthProperty">
+{
+  // length property
+  const text = document.createTextNode('Hello');
+  testing.expectEqual(5, text.length);
+  testing.expectEqual(5, text.data.length);
+
+  const empty = document.createTextNode('');
+  testing.expectEqual(0, empty.length);
+
+  const comment = document.createComment('test comment');
+  testing.expectEqual(12, comment.length);
+}
+</script>
+
+<script id="appendDataBasic">
+{
+  // appendData basic
+  const text = document.createTextNode('Hello');
+  text.appendData(' World');
+  testing.expectEqual('Hello World', text.data);
+  testing.expectEqual(11, text.length);
+}
+</script>
+
+<script id="appendDataEmpty">
+{
+  // appendData to empty
+  const text = document.createTextNode('');
+  text.appendData('First');
+  testing.expectEqual('First', text.data);
+
+  // appendData empty string
+  text.appendData('');
+  testing.expectEqual('First', text.data);
+}
+</script>
+
+<script id="deleteDataBasic">
+{
+  // deleteData from middle
+  const text = document.createTextNode('Hello World');
+  text.deleteData(5, 6); // Remove ' World'
+  testing.expectEqual('Hello', text.data);
+  testing.expectEqual(5, text.length);
+}
+</script>
+
+<script id="deleteDataStart">
+{
+  // deleteData from start
+  const text = document.createTextNode('Hello World');
+  text.deleteData(0, 6); // Remove 'Hello '
+  testing.expectEqual('World', text.data);
+}
+</script>
+
+<script id="deleteDataEnd">
+{
+  // deleteData from end
+  const text = document.createTextNode('Hello World');
+  text.deleteData(5, 100); // Remove ' World' (count exceeds length)
+  testing.expectEqual('Hello', text.data);
+}
+</script>
+
+<script id="deleteDataAll">
+{
+  // deleteData everything
+  const text = document.createTextNode('Hello');
+  text.deleteData(0, 5);
+  testing.expectEqual('', text.data);
+  testing.expectEqual(0, text.length);
+}
+</script>
+
+<script id="deleteDataZeroCount">
+{
+  // deleteData with count=0
+  const text = document.createTextNode('Hello');
+  text.deleteData(2, 0);
+  testing.expectEqual('Hello', text.data);
+}
+</script>
+
+<script id="deleteDataInvalidOffset">
+{
+  // deleteData with invalid offset
+  const text = document.createTextNode('Hello');
+  testing.expectError('IndexSizeError: Index or size is negative or greater than the allowed amount', () => text.deleteData(10, 5));
+  testing.expectEqual('Hello', text.data); // unchanged
+}
+</script>
+
+<script id="insertDataMiddle">
+{
+  // insertData in middle
+  const text = document.createTextNode('Hello');
+  text.insertData(5, ' World');
+  testing.expectEqual('Hello World', text.data);
+}
+</script>
+
+<script id="insertDataStart">
+{
+  // insertData at start
+  const text = document.createTextNode('World');
+  text.insertData(0, 'Hello ');
+  testing.expectEqual('Hello World', text.data);
+}
+</script>
+
+<script id="insertDataEnd">
+{
+  // insertData at end
+  const text = document.createTextNode('Hello');
+  text.insertData(5, ' World');
+  testing.expectEqual('Hello World', text.data);
+}
+</script>
+
+<script id="insertDataEmpty">
+{
+  // insertData into empty
+  const text = document.createTextNode('');
+  text.insertData(0, 'Hello');
+  testing.expectEqual('Hello', text.data);
+}
+</script>
+
+<script id="insertDataInvalidOffset">
+{
+  // insertData with invalid offset
+  const text = document.createTextNode('Hello');
+  testing.expectError('IndexSizeError: Index or size is negative or greater than the allowed amount', () => text.insertData(10, 'X'));
+  testing.expectEqual('Hello', text.data);
+}
+</script>
+
+<script id="replaceDataBasic">
+{
+  // replaceData basic
+  const text = document.createTextNode('Hello World');
+  text.replaceData(6, 5, 'Universe');
+  testing.expectEqual('Hello Universe', text.data);
+}
+</script>
+
+<script id="replaceDataShorter">
+{
+  // replaceData with shorter string
+  const text = document.createTextNode('Hello World');
+  text.replaceData(6, 5, 'Hi');
+  testing.expectEqual('Hello Hi', text.data);
+}
+</script>
+
+<script id="replaceDataLonger">
+{
+  // replaceData with longer string
+  const text = document.createTextNode('Hello Hi');
+  text.replaceData(6, 2, 'World');
+  testing.expectEqual('Hello World', text.data);
+}
+</script>
+
+<script id="replaceDataExceedingCount">
+{
+  // replaceData with count exceeding length
+  const text = document.createTextNode('Hello World');
+  text.replaceData(6, 100, 'Everyone');
+  testing.expectEqual('Hello Everyone', text.data);
+}
+</script>
+
+<script id="replaceDataZeroCount">
+{
+  // replaceData with count=0 (acts like insert)
+  const text = document.createTextNode('Hello World');
+  text.replaceData(5, 0, '!!!');
+  testing.expectEqual('Hello!!! World', text.data);
+}
+</script>
+
+<script id="substringDataBasic">
+{
+  // substringData basic
+  const text = document.createTextNode('Hello World');
+  const sub = text.substringData(0, 5);
+  testing.expectEqual('Hello', sub);
+  testing.expectEqual('Hello World', text.data); // original unchanged
+}
+</script>
+
+<script id="substringDataMiddle">
+{
+  // substringData from middle
+  const text = document.createTextNode('Hello World');
+  const sub = text.substringData(6, 5);
+  testing.expectEqual('World', sub);
+}
+</script>
+
+<script id="substringDataExceedingCount">
+{
+  // substringData with count exceeding length
+  const text = document.createTextNode('Hello World');
+  const sub = text.substringData(6, 100);
+  testing.expectEqual('World', sub);
+}
+</script>
+
+<script id="substringDataZeroCount">
+{
+  // substringData with count=0
+  const text = document.createTextNode('Hello');
+  const sub = text.substringData(0, 0);
+  testing.expectEqual('', sub);
+}
+</script>
+
+<script id="substringDataInvalidOffset">
+{
+  // substringData with invalid offset
+  const text = document.createTextNode('Hello');
+  testing.expectError('IndexSizeError: Index or size is negative or greater than the allowed amount', () => text.substringData(10, 5));
+}
+</script>
+
+<script id="commentCharacterData">
+{
+  // CharacterData methods work on comments too
+  const comment = document.createComment('Hello');
+
+  comment.appendData(' World');
+  testing.expectEqual('Hello World', comment.data);
+
+  comment.deleteData(5, 6);
+  testing.expectEqual('Hello', comment.data);
+
+  comment.insertData(0, 'Start: ');
+  testing.expectEqual('Start: Hello', comment.data);
+
+  comment.replaceData(0, 7, 'End: ');
+  testing.expectEqual('End: Hello', comment.data);
+
+  const sub = comment.substringData(5, 5);
+  testing.expectEqual('Hello', sub);
+}
+</script>
+
+<script id="dataChangeNotifications">
+{
+  // Verify data changes are reflected in DOM
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const text = document.createTextNode('Original');
+  container.appendChild(text);
+
+  text.appendData(' Text');
+  testing.expectEqual('Original Text', container.textContent);
+
+  text.deleteData(0, 9);
+  testing.expectEqual('Text', container.textContent);
+
+  text.data = 'Changed';
+  testing.expectEqual('Changed', container.textContent);
+}
+</script>
+
+<script id="removeWithSiblings">
+{
+  // remove() when node has siblings
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const text1 = document.createTextNode('A');
+  const text2 = document.createTextNode('B');
+  const text3 = document.createTextNode('C');
+  container.appendChild(text1);
+  container.appendChild(text2);
+  container.appendChild(text3);
+
+  testing.expectEqual(3, container.childNodes.length);
+  testing.expectEqual('ABC', container.textContent);
+
+  text2.remove();
+
+  testing.expectEqual(2, container.childNodes.length);
+  testing.expectEqual('AC', container.textContent);
+  testing.expectEqual(null, text2.parentNode);
+  testing.expectEqual(text3, text1.nextSibling);
+}
+</script>
+
+<script id="removeOnlyChild">
+{
+  // remove() when node is only child
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const text = document.createTextNode('Only');
+  container.appendChild(text);
+
+  testing.expectEqual(1, container.childNodes.length);
+
+  text.remove();
+
+  testing.expectEqual(0, container.childNodes.length);
+  testing.expectEqual(null, text.parentNode);
+}
+</script>
+
+<script id="removeNoParent">
+{
+  // remove() when node has no parent (should do nothing)
+  const text = document.createTextNode('Orphan');
+  text.remove(); // Should not throw
+  testing.expectEqual(null, text.parentNode);
+}
+</script>
+
+<script id="removeCommentWithElementSiblings">
+{
+  // remove() comment with element siblings
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const div1 = document.createElement('div');
+  div1.textContent = 'First';
+  const comment = document.createComment('middle');
+  const div2 = document.createElement('div');
+  div2.textContent = 'Last';
+
+  container.appendChild(div1);
+  container.appendChild(comment);
+  container.appendChild(div2);
+
+  testing.expectEqual(3, container.childNodes.length);
+
+  comment.remove();
+
+  testing.expectEqual(2, container.childNodes.length);
+  testing.expectEqual('DIV', container.childNodes[0].tagName);
+  testing.expectEqual('DIV', container.childNodes[1].tagName);
+  testing.expectEqual(div2, div1.nextSibling);
+}
+</script>
+
+<script id="beforeWithSiblings">
+{
+  // before() when node has siblings
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const text1 = document.createTextNode('A');
+  const text2 = document.createTextNode('C');
+  container.appendChild(text1);
+  container.appendChild(text2);
+
+  const textB = document.createTextNode('B');
+  text2.before(textB);
+
+  testing.expectEqual(3, container.childNodes.length);
+  testing.expectEqual('ABC', container.textContent);
+  testing.expectEqual(textB, text1.nextSibling);
+  testing.expectEqual(text2, textB.nextSibling);
+}
+</script>
+
+<script id="beforeMultipleNodes">
+{
+  // before() with multiple nodes
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const text = document.createTextNode('Z');
+  container.appendChild(text);
+
+  const text1 = document.createTextNode('A');
+  const text2 = document.createTextNode('B');
+  const text3 = document.createTextNode('C');
+
+  text.before(text1, text2, text3);
+
+  testing.expectEqual(4, container.childNodes.length);
+  testing.expectEqual('ABCZ', container.textContent);
+}
+</script>
+
+<script id="beforeMixedTypes">
+{
+  // before() with mixed node types
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const target = document.createTextNode('Target');
+  container.appendChild(target);
+
+  const elem = document.createElement('span');
+  elem.textContent = 'E';
+  const text = document.createTextNode('T');
+  const comment = document.createComment('C');
+
+  target.before(elem, text, comment);
+
+  testing.expectEqual(4, container.childNodes.length);
+  testing.expectEqual(1, container.childNodes[0].nodeType); // ELEMENT_NODE
+  testing.expectEqual(3, container.childNodes[1].nodeType); // TEXT_NODE
+  testing.expectEqual(8, container.childNodes[2].nodeType); // COMMENT_NODE
+  testing.expectEqual(3, container.childNodes[3].nodeType); // TEXT_NODE (target)
+}
+</script>
+
+<script id="beforeNoParent">
+{
+  // before() when node has no parent (should do nothing)
+  const orphan = document.createTextNode('Orphan');
+  const text = document.createTextNode('Test');
+  orphan.before(text);
+
+  testing.expectEqual(null, orphan.parentNode);
+  testing.expectEqual(null, text.parentNode);
+}
+</script>
+
+<script id="beforeOnlyChild">
+{
+  // before() when target is only child
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const target = document.createTextNode('B');
+  container.appendChild(target);
+
+  const textA = document.createTextNode('A');
+  target.before(textA);
+
+  testing.expectEqual(2, container.childNodes.length);
+  testing.expectEqual('AB', container.textContent);
+  testing.expectEqual(textA, container.firstChild);
+  testing.expectEqual(target, textA.nextSibling);
+}
+</script>
+
+<script id="afterWithSiblings">
+{
+  // after() when node has siblings
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const text1 = document.createTextNode('A');
+  const text2 = document.createTextNode('C');
+  container.appendChild(text1);
+  container.appendChild(text2);
+
+  const textB = document.createTextNode('B');
+  text1.after(textB);
+
+  testing.expectEqual(3, container.childNodes.length);
+  testing.expectEqual('ABC', container.textContent);
+  testing.expectEqual(textB, text1.nextSibling);
+  testing.expectEqual(text2, textB.nextSibling);
+}
+</script>
+
+<script id="afterMultipleNodes">
+{
+  // after() with multiple nodes
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const text = document.createTextNode('A');
+  container.appendChild(text);
+
+  const text1 = document.createTextNode('B');
+  const text2 = document.createTextNode('C');
+  const text3 = document.createTextNode('D');
+
+  text.after(text1, text2, text3);
+
+  testing.expectEqual(4, container.childNodes.length);
+  testing.expectEqual('ABCD', container.textContent);
+}
+</script>
+
+<script id="afterMixedTypes">
+{
+  // after() with mixed node types
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const target = document.createTextNode('Start');
+  container.appendChild(target);
+
+  const elem = document.createElement('div');
+  elem.textContent = 'E';
+  const comment = document.createComment('comment');
+  const text = document.createTextNode('T');
+
+  target.after(elem, comment, text);
+
+  testing.expectEqual(4, container.childNodes.length);
+  testing.expectEqual(3, container.childNodes[0].nodeType); // TEXT_NODE (target)
+  testing.expectEqual(1, container.childNodes[1].nodeType); // ELEMENT_NODE
+  testing.expectEqual(8, container.childNodes[2].nodeType); // COMMENT_NODE
+  testing.expectEqual(3, container.childNodes[3].nodeType); // TEXT_NODE
+}
+</script>
+
+<script id="afterNoParent">
+{
+  // after() when node has no parent (should do nothing)
+  const orphan = document.createTextNode('Orphan');
+  const text = document.createTextNode('Test');
+  orphan.after(text);
+
+  testing.expectEqual(null, orphan.parentNode);
+  testing.expectEqual(null, text.parentNode);
+}
+</script>
+
+<script id="afterAsLastChild">
+{
+  // after() when target is last child
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const target = document.createTextNode('A');
+  container.appendChild(target);
+
+  const textB = document.createTextNode('B');
+  target.after(textB);
+
+  testing.expectEqual(2, container.childNodes.length);
+  testing.expectEqual('AB', container.textContent);
+  testing.expectEqual(target, container.firstChild);
+  testing.expectEqual(textB, container.lastChild);
+  testing.expectEqual(null, textB.nextSibling);
+}
+</script>
+
+<script id="replaceWithSingleNode">
+{
+  // replaceWith() with single node
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const old = document.createTextNode('Old');
+  container.appendChild(old);
+
+  const replacement = document.createTextNode('New');
+  old.replaceWith(replacement);
+
+  testing.expectEqual(1, container.childNodes.length);
+  testing.expectEqual('New', container.textContent);
+  testing.expectEqual(null, old.parentNode);
+  testing.expectEqual(container, replacement.parentNode);
+}
+</script>
+
+<script id="replaceWithMultipleNodes">
+{
+  // replaceWith() with multiple nodes
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const old = document.createTextNode('X');
+  container.appendChild(old);
+
+  const text1 = document.createTextNode('A');
+  const text2 = document.createTextNode('B');
+  const text3 = document.createTextNode('C');
+
+  old.replaceWith(text1, text2, text3);
+
+  testing.expectEqual(3, container.childNodes.length);
+  testing.expectEqual('ABC', container.textContent);
+  testing.expectEqual(null, old.parentNode);
+}
+</script>
+
+<script id="replaceWithOnlyChild">
+{
+  // replaceWith() when target is only child
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const old = document.createTextNode('Only');
+  container.appendChild(old);
+
+  testing.expectEqual(1, container.childNodes.length);
+
+  const replacement = document.createTextNode('Replaced');
+  old.replaceWith(replacement);
+
+  testing.expectEqual(1, container.childNodes.length);
+  testing.expectEqual('Replaced', container.textContent);
+  testing.expectEqual(replacement, container.firstChild);
+}
+</script>
+
+<script id="replaceWithBetweenSiblings">
+{
+  // replaceWith() when node has siblings on both sides
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const text1 = document.createTextNode('A');
+  const text2 = document.createTextNode('X');
+  const text3 = document.createTextNode('C');
+  container.appendChild(text1);
+  container.appendChild(text2);
+  container.appendChild(text3);
+
+  const replacement = document.createTextNode('B');
+  text2.replaceWith(replacement);
+
+  testing.expectEqual(3, container.childNodes.length);
+  testing.expectEqual('ABC', container.textContent);
+  testing.expectEqual(replacement, text1.nextSibling);
+  testing.expectEqual(text3, replacement.nextSibling);
+}
+</script>
+
+<script id="replaceWithMixedTypes">
+{
+  // replaceWith() with mixed node types
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const old = document.createComment('old');
+  container.appendChild(old);
+
+  const elem = document.createElement('span');
+  elem.textContent = 'E';
+  const text = document.createTextNode('T');
+  const comment = document.createComment('C');
+
+  old.replaceWith(elem, text, comment);
+
+  testing.expectEqual(3, container.childNodes.length);
+  testing.expectEqual(1, container.childNodes[0].nodeType); // ELEMENT_NODE
+  testing.expectEqual(3, container.childNodes[1].nodeType); // TEXT_NODE
+  testing.expectEqual(8, container.childNodes[2].nodeType); // COMMENT_NODE
+  testing.expectEqual(null, old.parentNode);
+}
+</script>
+
+<script id="nextElementSiblingText">
+{
+  // nextElementSibling on text node with element siblings
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const text1 = document.createTextNode('A');
+  const comment = document.createComment('comment');
+  const div = document.createElement('div');
+  div.id = 'found';
+  const text2 = document.createTextNode('B');
+
+  container.appendChild(text1);
+  container.appendChild(comment);
+  container.appendChild(div);
+  container.appendChild(text2);
+
+  testing.expectEqual('found', text1.nextElementSibling.id);
+  testing.expectEqual('found', comment.nextElementSibling.id);
+  testing.expectEqual(null, text2.nextElementSibling);
+}
+</script>
+
+<script id="nextElementSiblingNoElement">
+{
+  // nextElementSibling when there's no element sibling
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const text = document.createTextNode('A');
+  const comment = document.createComment('B');
+  container.appendChild(text);
+  container.appendChild(comment);
+
+  testing.expectEqual(null, text.nextElementSibling);
+  testing.expectEqual(null, comment.nextElementSibling);
+}
+</script>
+
+<script id="previousElementSiblingComment">
+{
+  // previousElementSibling on comment with element siblings
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const div = document.createElement('div');
+  div.id = 'found';
+  const text = document.createTextNode('text');
+  const comment = document.createComment('comment');
+
+  container.appendChild(div);
+  container.appendChild(text);
+  container.appendChild(comment);
+
+  testing.expectEqual('found', text.previousElementSibling.id);
+  testing.expectEqual('found', comment.previousElementSibling.id);
+  testing.expectEqual(null, div.previousElementSibling);
+}
+</script>
+
+<script id="previousElementSiblingNoElement">
+{
+  // previousElementSibling when there's no element sibling
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const text = document.createTextNode('A');
+  const comment = document.createComment('B');
+  container.appendChild(text);
+  container.appendChild(comment);
+
+  testing.expectEqual(null, text.previousElementSibling);
+  testing.expectEqual(null, comment.previousElementSibling);
+}
+</script>
diff --git a/src/browser/tests/document_fragment/insertion.html b/src/browser/tests/document_fragment/insertion.html
new file mode 100644
index 00000000..f110766c
--- /dev/null
+++ b/src/browser/tests/document_fragment/insertion.html
@@ -0,0 +1,238 @@
+<!DOCTYPE html>
+<script src="../testing.js"></script>
+
+<div id="container"></div>
+
+<script id="appendChildBasic">
+{
+  // DocumentFragment children should be moved, fragment itself should not appear
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const fragment = document.createDocumentFragment();
+  const span1 = document.createElement('span');
+  span1.textContent = 'A';
+  const span2 = document.createElement('span');
+  span2.textContent = 'B';
+
+  fragment.appendChild(span1);
+  fragment.appendChild(span2);
+
+  // Fragment should have 2 children before insertion
+  testing.expectEqual(2, fragment.childNodes.length);
+
+  container.appendChild(fragment);
+
+  // After insertion:
+  // 1. Container should have 2 children (the spans), not 1 (the fragment)
+  testing.expectEqual(2, container.childNodes.length);
+  testing.expectEqual('SPAN', container.childNodes[0].tagName);
+  testing.expectEqual('SPAN', container.childNodes[1].tagName);
+  testing.expectEqual('A', container.childNodes[0].textContent);
+  testing.expectEqual('B', container.childNodes[1].textContent);
+
+  // 2. Fragment should be empty after insertion
+  testing.expectEqual(0, fragment.childNodes.length);
+
+  // 3. No DocumentFragment should appear in the tree
+  testing.expectEqual('SPAN', container.firstChild.tagName);
+  testing.expectEqual('SPAN', container.firstChild.nodeName);
+}
+</script>
+
+<script id="insertBeforeBasic">
+{
+  // insertBefore with DocumentFragment
+  const container = $('#container');
+  container.innerHTML = '<div id="ref">REF</div>';
+
+  const fragment = document.createDocumentFragment();
+  const span1 = document.createElement('span');
+  span1.textContent = 'A';
+  const span2 = document.createElement('span');
+  span2.textContent = 'B';
+
+  fragment.appendChild(span1);
+  fragment.appendChild(span2);
+
+  const ref = $('#ref');
+  container.insertBefore(fragment, ref);
+
+  // Container should have: span1, span2, ref (3 children)
+  testing.expectEqual(3, container.childNodes.length);
+  testing.expectEqual('SPAN', container.childNodes[0].tagName);
+  testing.expectEqual('A', container.childNodes[0].textContent);
+  testing.expectEqual('SPAN', container.childNodes[1].tagName);
+  testing.expectEqual('B', container.childNodes[1].textContent);
+  testing.expectEqual('DIV', container.childNodes[2].tagName);
+  testing.expectEqual('REF', container.childNodes[2].textContent);
+
+  // Fragment should be empty
+  testing.expectEqual(0, fragment.childNodes.length);
+}
+</script>
+
+<script id="insertBeforeNull">
+{
+  // insertBefore with null ref node should behave like appendChild
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const fragment = document.createDocumentFragment();
+  const span = document.createElement('span');
+  span.textContent = 'TEST';
+  fragment.appendChild(span);
+
+  container.insertBefore(fragment, null);
+
+  testing.expectEqual(1, container.childNodes.length);
+  testing.expectEqual('SPAN', container.childNodes[0].tagName);
+  testing.expectEqual(0, fragment.childNodes.length);
+}
+</script>
+
+<script id="replaceChildWithFragment">
+{
+  // replaceChild with DocumentFragment
+  const container = $('#container');
+  container.innerHTML = '<div id="old">OLD</div>';
+
+  const fragment = document.createDocumentFragment();
+  const span1 = document.createElement('span');
+  span1.textContent = 'A';
+  const span2 = document.createElement('span');
+  span2.textContent = 'B';
+  fragment.appendChild(span1);
+  fragment.appendChild(span2);
+
+  const old = $('#old');
+  container.replaceChild(fragment, old);
+
+  // Container should have 2 children (the fragment's children)
+  testing.expectEqual(2, container.childNodes.length);
+  testing.expectEqual('SPAN', container.childNodes[0].tagName);
+  testing.expectEqual('A', container.childNodes[0].textContent);
+  testing.expectEqual('SPAN', container.childNodes[1].tagName);
+  testing.expectEqual('B', container.childNodes[1].textContent);
+
+  // Old node should not be in container
+  testing.expectEqual(null, old.parentNode);
+}
+</script>
+
+<script id="emptyFragment">
+{
+  // Empty DocumentFragment should not add any nodes
+  const container = $('#container');
+  container.innerHTML = '<span>TEST</span>';
+
+  const fragment = document.createDocumentFragment();
+  container.appendChild(fragment);
+
+  // Should still have just 1 child
+  testing.expectEqual(1, container.childNodes.length);
+  testing.expectEqual('SPAN', container.childNodes[0].tagName);
+}
+</script>
+
+<script id="fragmentReuse">
+{
+  // DocumentFragment can be reused after its children are moved
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const fragment = document.createDocumentFragment();
+  const span1 = document.createElement('span');
+  span1.textContent = 'A';
+  fragment.appendChild(span1);
+
+  container.appendChild(fragment);
+  testing.expectEqual(1, container.childNodes.length);
+  testing.expectEqual(0, fragment.childNodes.length);
+
+  // Reuse the same fragment
+  const span2 = document.createElement('span');
+  span2.textContent = 'B';
+  fragment.appendChild(span2);
+
+  container.appendChild(fragment);
+  testing.expectEqual(2, container.childNodes.length);
+  testing.expectEqual('A', container.childNodes[0].textContent);
+  testing.expectEqual('B', container.childNodes[1].textContent);
+}
+</script>
+
+<script id="nestedFragments">
+{
+  // DocumentFragment containing another DocumentFragment
+  // (though this is unusual, the inner fragment should also be unwrapped)
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const outer = document.createDocumentFragment();
+  const inner = document.createDocumentFragment();
+
+  const span = document.createElement('span');
+  span.textContent = 'TEST';
+  inner.appendChild(span);
+
+  // Appending inner fragment to outer should move span to outer
+  outer.appendChild(inner);
+  testing.expectEqual(1, outer.childNodes.length);
+  testing.expectEqual('SPAN', outer.childNodes[0].tagName);
+  testing.expectEqual(0, inner.childNodes.length);
+
+  // Now append outer to container
+  container.appendChild(outer);
+  testing.expectEqual(1, container.childNodes.length);
+  testing.expectEqual('SPAN', container.childNodes[0].tagName);
+  testing.expectEqual(0, outer.childNodes.length);
+}
+</script>
+
+<script id="fragmentWithMixedContent">
+{
+  // DocumentFragment with text nodes, comments, and elements
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const fragment = document.createDocumentFragment();
+  fragment.appendChild(document.createTextNode('Text1'));
+  fragment.appendChild(document.createComment('comment'));
+  const div = document.createElement('div');
+  div.textContent = 'Div';
+  fragment.appendChild(div);
+  fragment.appendChild(document.createTextNode('Text2'));
+
+  testing.expectEqual(4, fragment.childNodes.length);
+
+  container.appendChild(fragment);
+
+  // All 4 nodes should be in container
+  testing.expectEqual(4, container.childNodes.length);
+  testing.expectEqual(3, container.childNodes[0].nodeType); // TEXT_NODE
+  testing.expectEqual(8, container.childNodes[1].nodeType); // COMMENT_NODE
+  testing.expectEqual(1, container.childNodes[2].nodeType); // ELEMENT_NODE
+  testing.expectEqual(3, container.childNodes[3].nodeType); // TEXT_NODE
+
+  testing.expectEqual(0, fragment.childNodes.length);
+}
+</script>
+
+<script id="innerHTML">
+{
+  // After a DocumentFragment is inserted, innerHTML should not show it
+  const container = $('#container');
+  container.innerHTML = '';
+
+  const fragment = document.createDocumentFragment();
+  const comment = document.createComment('test');
+  fragment.appendChild(comment);
+
+  container.appendChild(fragment);
+
+  // Should only see the comment, not a DocumentFragment wrapper
+  const html = container.innerHTML;
+  testing.expectEqual('<!--test-->', html);
+}
+</script>
diff --git a/src/browser/tests/net/request.html b/src/browser/tests/net/request.html
index c0028cf8..437c2630 100644
--- a/src/browser/tests/net/request.html
+++ b/src/browser/tests/net/request.html
@@ -45,6 +45,11 @@
   const req = new Request('https://example.com/api', { headers });
   testing.expectEqual('value', req.headers.get('X-Custom'));
 }
+
+{
+  const req = new Request('https://example.com/api', {headers: {over: '9000!'}});
+  testing.expectEqual('9000!', req.headers.get('over'));
+}
 </script>
 
 <script id=request_input>
@@ -102,3 +107,4 @@
   testing.expectEqual('https://example.com/custom', req.url);
 }
 </script>
+
diff --git a/src/browser/webapi/CData.zig b/src/browser/webapi/CData.zig
index cb39a70b..f02d51ca 100644
--- a/src/browser/webapi/CData.zig
+++ b/src/browser/webapi/CData.zig
@@ -79,6 +79,119 @@ pub fn format(self: *const CData, writer: *std.io.Writer) !void {
     };
 }
 
+pub fn getLength(self: *const CData) usize {
+    return self._data.len;
+}
+
+pub fn appendData(self: *CData, data: []const u8, page: *Page) !void {
+    const new_data = try std.mem.concat(page.arena, u8, &.{ self._data, data });
+    try self.setData(new_data, page);
+}
+
+pub fn deleteData(self: *CData, offset: usize, count: usize, page: *Page) !void {
+    if (offset > self._data.len) return error.IndexSizeError;
+    const end = @min(offset + count, self._data.len);
+
+    // Just slice - original data stays in arena
+    const old_value = self._data;
+    if (offset == 0) {
+        self._data = self._data[end..];
+    } else if (end >= self._data.len) {
+        self._data = self._data[0..offset];
+    } else {
+        self._data = try std.mem.concat(page.arena, u8, &.{
+            self._data[0..offset],
+            self._data[end..],
+        });
+    }
+    page.characterDataChange(self.asNode(), old_value);
+}
+
+pub fn insertData(self: *CData, offset: usize, data: []const u8, page: *Page) !void {
+    if (offset > self._data.len) return error.IndexSizeError;
+    const new_data = try std.mem.concat(page.arena, u8, &.{
+        self._data[0..offset],
+        data,
+        self._data[offset..],
+    });
+    try self.setData(new_data, page);
+}
+
+pub fn replaceData(self: *CData, offset: usize, count: usize, data: []const u8, page: *Page) !void {
+    if (offset > self._data.len) return error.IndexSizeError;
+    const end = @min(offset + count, self._data.len);
+    const new_data = try std.mem.concat(page.arena, u8, &.{
+        self._data[0..offset],
+        data,
+        self._data[end..],
+    });
+    try self.setData(new_data, page);
+}
+
+pub fn substringData(self: *const CData, offset: usize, count: usize) ![]const u8 {
+    if (offset > self._data.len) return error.IndexSizeError;
+    const end = @min(offset + count, self._data.len);
+    return self._data[offset..end];
+}
+
+pub fn remove(self: *CData, page: *Page) !void {
+    const node = self.asNode();
+    const parent = node.parentNode() orelse return;
+    _ = try parent.removeChild(node, page);
+}
+
+pub fn before(self: *CData, nodes: []const Node.NodeOrText, page: *Page) !void {
+    const node = self.asNode();
+    const parent = node.parentNode() orelse return;
+
+    for (nodes) |node_or_text| {
+        const child = try node_or_text.toNode(page);
+        _ = try parent.insertBefore(child, node, page);
+    }
+}
+
+pub fn after(self: *CData, nodes: []const Node.NodeOrText, page: *Page) !void {
+    const node = self.asNode();
+    const parent = node.parentNode() orelse return;
+    const next = node.nextSibling();
+
+    for (nodes) |node_or_text| {
+        const child = try node_or_text.toNode(page);
+        _ = try parent.insertBefore(child, next, page);
+    }
+}
+
+pub fn replaceWith(self: *CData, nodes: []const Node.NodeOrText, page: *Page) !void {
+    const node = self.asNode();
+    const parent = node.parentNode() orelse return;
+    const next = node.nextSibling();
+
+    _ = try parent.removeChild(node, page);
+
+    for (nodes) |node_or_text| {
+        const child = try node_or_text.toNode(page);
+        _ = try parent.insertBefore(child, next, page);
+    }
+}
+
+pub fn nextElementSibling(self: *CData) ?*Node.Element {
+    var maybe_sibling = self.asNode().nextSibling();
+    while (maybe_sibling) |sibling| {
+        if (sibling.is(Node.Element)) |el| return el;
+        maybe_sibling = sibling.nextSibling();
+    }
+    return null;
+}
+
+pub fn previousElementSibling(self: *CData) ?*Node.Element {
+    var maybe_sibling = self.asNode().previousSibling();
+    while (maybe_sibling) |sibling| {
+        if (sibling.is(Node.Element)) |el| return el;
+        maybe_sibling = sibling.previousSibling();
+    }
+    return null;
+}
+
 pub const JsApi = struct {
     pub const bridge = js.Bridge(CData);
 
@@ -89,4 +202,24 @@ pub const JsApi = struct {
     };
 
     pub const data = bridge.accessor(CData.getData, CData.setData, .{});
+    pub const length = bridge.accessor(CData.getLength, null, .{});
+
+    pub const appendData = bridge.function(CData.appendData, .{});
+    pub const deleteData = bridge.function(CData.deleteData, .{ .dom_exception = true });
+    pub const insertData = bridge.function(CData.insertData, .{ .dom_exception = true });
+    pub const replaceData = bridge.function(CData.replaceData, .{ .dom_exception = true });
+    pub const substringData = bridge.function(CData.substringData, .{ .dom_exception = true });
+
+    pub const remove = bridge.function(CData.remove, .{});
+    pub const before = bridge.function(CData.before, .{});
+    pub const after = bridge.function(CData.after, .{});
+    pub const replaceWith = bridge.function(CData.replaceWith, .{});
+
+    pub const nextElementSibling = bridge.accessor(CData.nextElementSibling, null, .{});
+    pub const previousElementSibling = bridge.accessor(CData.previousElementSibling, null, .{});
 };
+
+const testing = @import("../../testing.zig");
+test "WebApi: CData" {
+    try testing.htmlRunner("cdata", .{});
+}
diff --git a/src/browser/webapi/DOMException.zig b/src/browser/webapi/DOMException.zig
index 2f1cc789..72d79559 100644
--- a/src/browser/webapi/DOMException.zig
+++ b/src/browser/webapi/DOMException.zig
@@ -33,6 +33,7 @@ pub fn fromError(err: anyerror) ?DOMException {
         error.NotFound => .{ ._code = .not_found },
         error.NotSupported => .{ ._code = .not_supported },
         error.HierarchyError => .{ ._code = .hierarchy_error },
+        error.IndexSizeError => .{ ._code = .index_size_error },
         else => null,
     };
 }
@@ -45,6 +46,7 @@ pub fn getName(self: *const DOMException) []const u8 {
     return switch (self._code) {
         .none => "Error",
         .invalid_character_error => "InvalidCharacterError",
+        .index_size_error => "IndexSizeErorr",
         .syntax_error => "SyntaxError",
         .not_found => "NotFoundError",
         .not_supported => "NotSupportedError",
@@ -56,6 +58,7 @@ pub fn getMessage(self: *const DOMException) []const u8 {
     return switch (self._code) {
         .none => "",
         .invalid_character_error => "Invalid Character",
+        .index_size_error => "IndexSizeError: Index or size is negative or greater than the allowed amount",
         .syntax_error => "Syntax Error",
         .not_supported => "Not Supported",
         .not_found => "Not Found",
@@ -65,6 +68,7 @@ pub fn getMessage(self: *const DOMException) []const u8 {
 
 const Code = enum(u8) {
     none = 0,
+    index_size_error = 1,
     hierarchy_error = 3,
     invalid_character_error = 5,
     not_found = 8,
diff --git a/src/browser/webapi/Element.zig b/src/browser/webapi/Element.zig
index 40240953..b3847bc1 100644
--- a/src/browser/webapi/Element.zig
+++ b/src/browser/webapi/Element.zig
@@ -26,17 +26,18 @@ const Page = @import("../Page.zig");
 const reflect = @import("../reflect.zig");
 
 const Node = @import("Node.zig");
+const CSS = @import("CSS.zig");
+const DOMRect = @import("DOMRect.zig");
+const ShadowRoot = @import("ShadowRoot.zig");
 const collections = @import("collections.zig");
 const Selector = @import("selector/Selector.zig");
-pub const Attribute = @import("element/Attribute.zig");
+const Animation = @import("animation/Animation.zig");
+const DOMStringMap = @import("element/DOMStringMap.zig");
 const CSSStyleProperties = @import("css/CSSStyleProperties.zig");
-pub const DOMStringMap = @import("element/DOMStringMap.zig");
-const DOMRect = @import("DOMRect.zig");
-const CSS = @import("CSS.zig");
-const ShadowRoot = @import("ShadowRoot.zig");
 
 pub const Svg = @import("element/Svg.zig");
 pub const Html = @import("element/Html.zig");
+pub const Attribute = @import("element/Attribute.zig");
 
 const Element = @This();
 
@@ -587,6 +588,14 @@ pub fn querySelectorAll(self: *Element, input: []const u8, page: *Page) !*Select
     return Selector.querySelectorAll(self.asNode(), input, page);
 }
 
+pub fn getAnimations(_: *const Element) []*Animation {
+    return &.{};
+}
+
+pub fn animate(_: *Element, _: js.Object, _: js.Object) !Animation {
+    return Animation.init();
+}
+
 pub fn closest(self: *Element, selector: []const u8, page: *Page) !?*Element {
     if (selector.len == 0) {
         return error.SyntaxError;
@@ -1012,6 +1021,8 @@ pub const JsApi = struct {
     pub const querySelector = bridge.function(Element.querySelector, .{ .dom_exception = true });
     pub const querySelectorAll = bridge.function(Element.querySelectorAll, .{ .dom_exception = true });
     pub const closest = bridge.function(Element.closest, .{ .dom_exception = true });
+    pub const getAnimations = bridge.function(Element.getAnimations, .{});
+    pub const animate = bridge.function(Element.animate, .{});
     pub const checkVisibility = bridge.function(Element.checkVisibility, .{});
     pub const getBoundingClientRect = bridge.function(Element.getBoundingClientRect, .{});
     pub const getElementsByTagName = bridge.function(Element.getElementsByTagName, .{});
diff --git a/src/browser/webapi/KeyValueList.zig b/src/browser/webapi/KeyValueList.zig
index c9eb70c8..4ec85f20 100644
--- a/src/browser/webapi/KeyValueList.zig
+++ b/src/browser/webapi/KeyValueList.zig
@@ -41,9 +41,40 @@ pub const empty: KeyValueList = .{
     ._entries = .empty,
 };
 
+pub fn copy(arena: Allocator, original: KeyValueList) !KeyValueList {
+    var list = KeyValueList.init();
+    try list.ensureTotalCapacity(arena, original.len());
+    for (original._entries.items) |entry| {
+        try list.appendAssumeCapacity(arena, entry.name.str(), entry.value.str());
+    }
+    return list;
+}
+
+pub fn fromJsObject(arena: Allocator, js_obj: js.Object) !KeyValueList {
+    var it = js_obj.nameIterator();
+    var list = KeyValueList.init();
+    try list.ensureTotalCapacity(arena, it.count);
+
+    while (try it.next()) |name| {
+        const js_value = try js_obj.get(name);
+        const value = try js_value.toString(arena);
+
+        try list._entries.append(arena, .{
+            .name = try String.init(arena, name, .{}),
+            .value = try String.init(arena, value, .{}),
+        });
+    }
+
+    return list;
+}
+
 pub const Entry = struct {
     name: String,
     value: String,
+
+    pub fn format(self: Entry, writer: *std.Io.Writer) !void {
+        return writer.print("{f}: {f}", .{ self.name, self.value });
+    }
 };
 
 pub fn init() KeyValueList {
diff --git a/src/browser/webapi/Node.zig b/src/browser/webapi/Node.zig
index ab0c28ec..8e65a5e9 100644
--- a/src/browser/webapi/Node.zig
+++ b/src/browser/webapi/Node.zig
@@ -143,7 +143,6 @@ pub fn parentElement(self: *const Node) ?*Element {
 }
 
 pub fn appendChild(self: *Node, child: *Node, page: *Page) !*Node {
-    // Special case: DocumentFragment - append all its children instead
     if (child.is(DocumentFragment)) |_| {
         try page.appendAllChildren(child, self);
         return child;
@@ -338,6 +337,11 @@ pub fn insertBefore(self: *Node, new_node: *Node, ref_node_: ?*Node, page: *Page
         return error.NotFound;
     }
 
+    if (new_node.is(DocumentFragment)) |_| {
+        try page.insertAllChildrenBefore(new_node, self, ref_node);
+        return new_node;
+    }
+
     const child_already_connected = new_node.isConnected();
 
     page.domChanged();
diff --git a/src/browser/webapi/Window.zig b/src/browser/webapi/Window.zig
index ad755b44..250abb26 100644
--- a/src/browser/webapi/Window.zig
+++ b/src/browser/webapi/Window.zig
@@ -157,7 +157,7 @@ pub fn setOnUnhandledRejection(self: *Window, cb_: ?js.Function) !void {
     }
 }
 
-pub fn fetch(_: *const Window, input: Fetch.Input, options: ?Fetch.RequestInit, page: *Page) !js.Promise {
+pub fn fetch(_: *const Window, input: Fetch.Input, options: ?Fetch.InitOpts, page: *Page) !js.Promise {
     return Fetch.init(input, options, page);
 }
 
diff --git a/src/browser/webapi/animation/Animation.zig b/src/browser/webapi/animation/Animation.zig
new file mode 100644
index 00000000..2fecfa95
--- /dev/null
+++ b/src/browser/webapi/animation/Animation.zig
@@ -0,0 +1,49 @@
+// Copyright (C) 2023-2025  Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+const js = @import("../../js/js.zig");
+const Page = @import("../../Page.zig");
+
+const Animation = @This();
+
+pub fn init() !Animation {
+    return .{};
+}
+
+pub fn play(_: *Animation) void {}
+pub fn pause(_: *Animation) void {}
+pub fn cancel(_: *Animation) void {}
+pub fn finish(_: *Animation) void {}
+pub fn reverse(_: *Animation) void {}
+
+pub const JsApi = struct {
+    pub const bridge = js.Bridge(Animation);
+
+    pub const Meta = struct {
+        pub const name = "Animation";
+        pub const prototype_chain = bridge.prototypeChain();
+        pub var class_id: bridge.ClassId = undefined;
+        pub const empty_with_no_proto = true;
+    };
+
+    pub const play = bridge.function(Animation.play, .{});
+    pub const pause = bridge.function(Animation.pause, .{});
+    pub const cancel = bridge.function(Animation.cancel, .{});
+    pub const finish = bridge.function(Animation.finish, .{});
+    pub const reverse = bridge.function(Animation.reverse, .{});
+};
diff --git a/src/browser/webapi/net/Fetch.zig b/src/browser/webapi/net/Fetch.zig
index 0f6c37f3..50d44270 100644
--- a/src/browser/webapi/net/Fetch.zig
+++ b/src/browser/webapi/net/Fetch.zig
@@ -40,10 +40,10 @@ _response: *Response,
 _resolver: js.PersistentPromiseResolver,
 
 pub const Input = Request.Input;
-pub const RequestInit = Request.Options;
+pub const InitOpts = Request.InitOpts;
 
 // @ZIGDOM just enough to get campfire demo working
-pub fn init(input: Input, options: ?RequestInit, page: *Page) !js.Promise {
+pub fn init(input: Input, options: ?InitOpts, page: *Page) !js.Promise {
     const request = try Request.init(input, options, page);
 
     const fetch = try page.arena.create(Fetch);
@@ -56,7 +56,11 @@ pub fn init(input: Input, options: ?RequestInit, page: *Page) !js.Promise {
     };
 
     const http_client = page._session.browser.http_client;
-    const headers = try http_client.newHeaders();
+    var headers = try http_client.newHeaders();
+    if (request._headers) |h| {
+        try h.populateHttpHeader(page.call_arena, &headers);
+    }
+    try page.requestCookie(.{}).headersForRequest(page.arena, request._url, &headers);
 
     if (comptime IS_DEBUG) {
         log.debug(.http, "fetch", .{ .url = request._url });
diff --git a/src/browser/webapi/net/Headers.zig b/src/browser/webapi/net/Headers.zig
index 136207bd..63377179 100644
--- a/src/browser/webapi/net/Headers.zig
+++ b/src/browser/webapi/net/Headers.zig
@@ -5,16 +5,34 @@ const log = @import("../../../log.zig");
 const Page = @import("../../Page.zig");
 const KeyValueList = @import("../KeyValueList.zig");
 
+const Allocator = std.mem.Allocator;
+
 const Headers = @This();
 
 _list: KeyValueList,
 
-pub fn init(page: *Page) !*Headers {
+pub const InitOpts = union(enum) {
+    obj: *Headers,
+    js_obj: js.Object,
+};
+
+pub fn init(opts_: ?InitOpts, page: *Page) !*Headers {
+    const list = if (opts_) |opts| switch (opts) {
+        .obj => |obj| try KeyValueList.copy(page.arena, obj._list),
+        .js_obj => |js_obj| try KeyValueList.fromJsObject(page.arena, js_obj),
+    } else KeyValueList.init();
+
     return page._factory.create(Headers{
-        ._list = KeyValueList.init(),
+        ._list = list,
     });
 }
 
+// pub fn fromJsObject(js_obj: js.Object, page: *Page) !*Headers {
+//     return page._factory.create(Headers{
+//         ._list = try KeyValueList.fromJsObject(page.arena, js_obj),
+//     });
+// }
+
 pub fn append(self: *Headers, name: []const u8, value: []const u8, page: *Page) !void {
     const normalized_name = normalizeHeaderName(name, page);
     try self._list.append(page.arena, normalized_name, value);
@@ -63,6 +81,15 @@ pub fn forEach(self: *Headers, cb_: js.Function, js_this_: ?js.Object) !void {
     }
 }
 
+// TODO: do we really need 2 different header structs??
+const Http = @import("../../../http/Http.zig");
+pub fn populateHttpHeader(self: *Headers, allocator: Allocator, http_headers: *Http.Headers) !void {
+    for (self._list._entries.items) |entry| {
+        const merged = try std.mem.concatWithSentinel(allocator, u8, &.{ entry.name.str(), ": ", entry.value.str() }, 0);
+        try http_headers.add(merged);
+    }
+}
+
 fn normalizeHeaderName(name: []const u8, page: *Page) []const u8 {
     if (name.len > page.buf.len) {
         return name;
diff --git a/src/browser/webapi/net/Request.zig b/src/browser/webapi/net/Request.zig
index d1524afe..9ca84c41 100644
--- a/src/browser/webapi/net/Request.zig
+++ b/src/browser/webapi/net/Request.zig
@@ -37,19 +37,19 @@ pub const Input = union(enum) {
     url: [:0]const u8,
 };
 
-pub const Options = struct {
+pub const InitOpts = struct {
     method: ?[]const u8 = null,
-    headers: ?*Headers = null,
+    headers: ?Headers.InitOpts = null,
 };
 
-pub fn init(input: Input, opts_: ?Options, page: *Page) !*Request {
+pub fn init(input: Input, opts_: ?InitOpts, page: *Page) !*Request {
     const arena = page.arena;
     const url = switch (input) {
         .url => |u| try URL.resolve(arena, page.url, u, .{ .always_dupe = true }),
         .request => |r| try arena.dupeZ(u8, r._url),
     };
 
-    const opts = opts_ orelse Options{};
+    const opts = opts_ orelse InitOpts{};
     const method = if (opts.method) |m|
         try parseMethod(m, page)
     else switch (input) {
@@ -57,8 +57,8 @@ pub fn init(input: Input, opts_: ?Options, page: *Page) !*Request {
         .request => |r| r._method,
     };
 
-    const headers = if (opts.headers) |h|
-        h
+    const headers = if (opts.headers) |header_init|
+        try Headers.init(header_init, page)
     else switch (input) {
         .url => null,
         .request => |r| r._headers,
@@ -103,7 +103,7 @@ pub fn getHeaders(self: *Request, page: *Page) !*Headers {
         return headers;
     }
 
-    const headers = try Headers.init(page);
+    const headers = try Headers.init(null, page);
     self._headers = headers;
     return headers;
 }
diff --git a/src/browser/webapi/net/Response.zig b/src/browser/webapi/net/Response.zig
index 24447566..fe464320 100644
--- a/src/browser/webapi/net/Response.zig
+++ b/src/browser/webapi/net/Response.zig
@@ -56,7 +56,7 @@ pub fn init(body_: ?[]const u8, opts_: ?InitOpts, page: *Page) !*Response {
         ._arena = page.arena,
         ._status = opts.status,
         ._body = body,
-        ._headers = opts.headers orelse try Headers.init(page),
+        ._headers = opts.headers orelse try Headers.init(null, page),
         ._type = .basic, // @ZIGDOM: todo
     });
 }
diff --git a/src/browser/webapi/net/URLSearchParams.zig b/src/browser/webapi/net/URLSearchParams.zig
index 9bdecd2e..73e5e110 100644
--- a/src/browser/webapi/net/URLSearchParams.zig
+++ b/src/browser/webapi/net/URLSearchParams.zig
@@ -45,7 +45,7 @@ pub fn init(opts_: ?InitOpts, page: *Page) !*URLSearchParams {
             .query_string => |qs| break :blk try paramsFromString(arena, qs, &page.buf),
             .value => |js_val| {
                 if (js_val.isObject()) {
-                    break :blk try paramsFromObject(arena, js_val.toObject());
+                    break :blk try KeyValueList.fromJsObject(arena, js_val.toObject());
                 }
                 if (js_val.isString()) {
                     break :blk try paramsFromString(arena, try js_val.toString(arena), &page.buf);
@@ -187,25 +187,6 @@ fn paramsFromString(allocator: Allocator, input_: []const u8, buf: []u8) !KeyVal
     return params;
 }
 
-fn paramsFromObject(arena: Allocator, js_obj: js.Object) !KeyValueList {
-    var it = js_obj.nameIterator(arena);
-
-    var params = KeyValueList.init();
-    try params.ensureTotalCapacity(arena, it.count);
-
-    while (try it.next()) |name| {
-        const js_value = try js_obj.get(name);
-        const value = try js_value.toString(arena);
-
-        try params._entries.append(arena, .{
-            .name = try String.init(arena, name, .{}),
-            .value = try String.init(arena, value, .{}),
-        });
-    }
-
-    return params;
-}
-
 fn unescape(arena: Allocator, value: []const u8, buf: []u8) !String {
     if (value.len == 0) {
         return String.init(undefined, "", .{});
diff --git a/src/browser/webapi/net/XMLHttpRequest.zig b/src/browser/webapi/net/XMLHttpRequest.zig
index 4b0cdb9f..4959d563 100644
--- a/src/browser/webapi/net/XMLHttpRequest.zig
+++ b/src/browser/webapi/net/XMLHttpRequest.zig
@@ -26,6 +26,7 @@ const URL = @import("../../URL.zig");
 const Mime = @import("../../Mime.zig");
 const Page = @import("../../Page.zig");
 const Event = @import("../Event.zig");
+const Headers = @import("Headers.zig");
 const EventTarget = @import("../EventTarget.zig");
 const XMLHttpRequestEventTarget = @import("XMLHttpRequestEventTarget.zig");
 
@@ -40,6 +41,7 @@ _transfer: ?*Http.Transfer = null,
 
 _url: [:0]const u8 = "",
 _method: Http.Method = .GET,
+_request_headers: *Headers,
 _request_body: ?[]const u8 = null,
 
 _response: std.ArrayList(u8) = .empty,
@@ -71,6 +73,7 @@ pub fn init(page: *Page) !*XMLHttpRequest {
         ._page = page,
         ._proto = undefined,
         ._arena = page.arena,
+        ._request_headers = try Headers.init(null, page),
     });
 }
 
@@ -129,6 +132,10 @@ pub fn open(self: *XMLHttpRequest, method_: []const u8, url: [:0]const u8) !void
     try self.stateChanged(.opened, self._page);
 }
 
+pub fn setRequestHeader(self: *XMLHttpRequest, name: []const u8, value: []const u8, page: *Page) !void {
+    return self._request_headers.append(name, value, page);
+}
+
 pub fn send(self: *XMLHttpRequest, body_: ?[]const u8) !void {
     if (comptime IS_DEBUG) {
         log.debug(.http, "XMLHttpRequest.send", .{ .url = self._url });
@@ -143,10 +150,7 @@ pub fn send(self: *XMLHttpRequest, body_: ?[]const u8) !void {
     const page = self._page;
     const http_client = page._session.browser.http_client;
     var headers = try http_client.newHeaders();
-    // @ZIGDOM
-    // for (self._headers.items) |hdr| {
-    //     try headers.add(hdr);
-    // }
+    try self._request_headers.populateHttpHeader(page.call_arena, &headers);
     try page.requestCookie(.{}).headersForRequest(self._arena, self._url, &headers);
 
     try http_client.request(.{
@@ -351,6 +355,7 @@ pub const JsApi = struct {
     pub const responseType = bridge.accessor(XMLHttpRequest.getResponseType, XMLHttpRequest.setResponseType, .{});
     pub const status = bridge.accessor(XMLHttpRequest.getStatus, null, .{});
     pub const response = bridge.accessor(XMLHttpRequest.getResponse, null, .{});
+    pub const setRequestHeader = bridge.function(XMLHttpRequest.setRequestHeader, .{});
 };
 
 const testing = @import("../../../testing.zig");