element: add prefix and localName accessors

src/browser/tests/document/create_element_ns.html

@@ -28,5 +28,13 @@
 
   const regularDiv = document.createElement('div');
   testing.expectEqual('DIV', regularDiv.tagName);
+  testing.expectEqual('div', regularDiv.localName);
+  testing.expectEqual(null, regularDiv.prefix);
   testing.expectEqual('http://www.w3.org/1999/xhtml', regularDiv.namespaceURI);
+
+  const custom = document.createElementNS('test', 'te:ST');
+  testing.expectEqual('TE:ST', custom.tagName); // Should be te:ST
+  testing.expectEqual('te', custom.prefix);
+  testing.expectEqual('ST', custom.localName);
+  testing.expectEqual('http://www.w3.org/1999/xhtml', custom.namespaceURI); // Should be test
 </script>

src/browser/webapi/Element.zig

@@ -913,6 +913,26 @@ pub const JsApi = struct {
         return buf.written();
     }
 
+    pub const prefix = bridge.accessor(_prefix, null, .{});
+    fn _prefix(self: *Element) ?[]const u8 {
+        const name = self.getTagNameLower();
+        if (std.mem.indexOfPos(u8, name, 0, ":")) |pos| {
+            return name[0..pos];
+        }
+
+        return null;
+    }
+
+    pub const localName = bridge.accessor(_localName, null, .{});
+    fn _localName(self: *Element) []const u8 {
+        const name = self.getTagNameLower();
+        if (std.mem.indexOfPos(u8, name, 0, ":")) |pos| {
+            return name[pos + 1 ..];
+        }
+
+        return name;
+    }
+
     pub const id = bridge.accessor(Element.getId, Element.setId, .{});
     pub const className = bridge.accessor(Element.getClassName, Element.setClassName, .{});
     pub const classList = bridge.accessor(Element.getClassList, null, .{});