Merge pull request #1749 from lightpanda-io/empty_is_and_where_pseudoselector

Empty :is() and :where() pseudoselectors are valid (and return nothing)

src/browser/tests/element/pseudo_classes.html

@@ -81,6 +81,17 @@
 }
 </script>
 
+<script id="is_empty">
+{
+    // Empty :is() and :where() are valid per spec and match nothing
+    const isEmptyResult = document.querySelectorAll(':is()');
+    testing.expectEqual(0, isEmptyResult.length);
+
+    const whereEmptyResult = document.querySelectorAll(':where()');
+    testing.expectEqual(0, whereEmptyResult.length);
+}
+</script>
+
 <div id=escaped class=":popover-open"></div>
 <script id="escaped">
 {

src/browser/tests/element/selector_invalid.html

@@ -12,8 +12,6 @@
     // Empty functional pseudo-classes should error
     testing.expectError("Error: InvalidPseudoClass", () => container.querySelector(':has()'));
     testing.expectError("Error: InvalidPseudoClass", () => container.querySelector(':not()'));
-    testing.expectError("Error: InvalidPseudoClass", () => container.querySelector(':is()'));
-    testing.expectError("Error: InvalidPseudoClass", () => container.querySelector(':where()'));
     testing.expectError("Error: InvalidPseudoClass", () => container.querySelector(':lang()'));
 }
 </script>

src/browser/webapi/selector/Parser.zig

@@ -487,7 +487,7 @@ fn pseudoClass(self: *Parser, arena: Allocator, page: *Page) !Selector.PseudoCla
             if (self.peek() != ')') return error.InvalidPseudoClass;
             self.input = self.input[1..];
 
-            if (selectors.items.len == 0) return error.InvalidPseudoClass;
+            // Empty :is() is valid per spec - matches nothing
             return .{ .is = selectors.items };
         }
 
@@ -514,7 +514,7 @@ fn pseudoClass(self: *Parser, arena: Allocator, page: *Page) !Selector.PseudoCla
             if (self.peek() != ')') return error.InvalidPseudoClass;
             self.input = self.input[1..];
 
-            if (selectors.items.len == 0) return error.InvalidPseudoClass;
+            // Empty :where() is valid per spec - matches nothing
             return .{ .where = selectors.items };
         }