diff --git a/src/browser/css/parser.zig b/src/browser/css/parser.zig
index 70fe20a07..4bcf7f9f1 100644
--- a/src/browser/css/parser.zig
+++ b/src/browser/css/parser.zig
@@ -605,6 +605,7 @@ pub const Parser = struct {
             .after, .backdrop, .before, .cue, .first_letter => return .{ .pseudo_element = pseudo_class },
             .first_line, .grammar_error, .marker, .placeholder => return .{ .pseudo_element = pseudo_class },
             .selection, .spelling_error => return .{ .pseudo_element = pseudo_class },
+            .modal => return .{ .pseudo_element = pseudo_class },
         }
     }
 
diff --git a/src/browser/css/selector.zig b/src/browser/css/selector.zig
index a3e372468..301af641d 100644
--- a/src/browser/css/selector.zig
+++ b/src/browser/css/selector.zig
@@ -98,6 +98,7 @@ pub const PseudoClass = enum {
     placeholder,
     selection,
     spelling_error,
+    modal,
 
     pub const Error = error{
         InvalidPseudoClass,
@@ -154,6 +155,7 @@ pub const PseudoClass = enum {
         if (std.ascii.eqlIgnoreCase(s, "placeholder")) return .placeholder;
         if (std.ascii.eqlIgnoreCase(s, "selection")) return .selection;
         if (std.ascii.eqlIgnoreCase(s, "spelling-error")) return .spelling_error;
+        if (std.ascii.eqlIgnoreCase(s, "modal")) return .modal;
         return Error.InvalidPseudoClass;
     }
 };
diff --git a/src/browser/cssom/css_style_declaration.zig b/src/browser/cssom/css_style_declaration.zig
index 1e980fb24..98a9015d5 100644
--- a/src/browser/cssom/css_style_declaration.zig
+++ b/src/browser/cssom/css_style_declaration.zig
@@ -85,7 +85,7 @@ pub const CSSStyleDeclaration = struct {
         return self.order.items.len;
     }
 
-    pub fn get_parentRule() ?CSSRule {
+    pub fn get_parentRule(_: *const CSSStyleDeclaration) ?CSSRule {
         return null;
     }
 
diff --git a/src/browser/dom/document.zig b/src/browser/dom/document.zig
index bc8dccbce..fe4a499ac 100644
--- a/src/browser/dom/document.zig
+++ b/src/browser/dom/document.zig
@@ -18,6 +18,7 @@
 
 const std = @import("std");
 
+const log = @import("../../log.zig");
 const parser = @import("../netsurf.zig");
 const Page = @import("../page.zig").Page;
 
@@ -120,9 +121,28 @@ pub const Document = struct {
         return try Element.toInterface(e);
     }
 
-    pub fn _createElement(self: *parser.Document, tag_name: []const u8) !ElementUnion {
-        const e = try parser.documentCreateElement(self, tag_name);
-        return try Element.toInterface(e);
+    const CreateElementResult = union(enum) {
+        element: ElementUnion,
+        custom: Env.JsObject,
+    };
+
+    pub fn _createElement(self: *parser.Document, tag_name: []const u8, page: *Page) !CreateElementResult {
+        const custom_element = page.window.custom_elements._get(tag_name) orelse {
+            const e = try parser.documentCreateElement(self, tag_name);
+            return .{ .element = try Element.toInterface(e) };
+        };
+
+        var result: Env.Function.Result = undefined;
+        const js_obj = custom_element.newInstance(&result) catch |err| {
+            log.fatal(.user_script, "newInstance error", .{
+                .err = result.exception,
+                .stack = result.stack,
+                .tag_name = tag_name,
+                .source = "createElement",
+            });
+            return err;
+        };
+        return .{ .custom = js_obj };
     }
 
     pub fn _createElementNS(self: *parser.Document, ns: []const u8, tag_name: []const u8) !ElementUnion {
diff --git a/src/browser/env.zig b/src/browser/env.zig
index 7d6627ec3..806391e5e 100644
--- a/src/browser/env.zig
+++ b/src/browser/env.zig
@@ -33,6 +33,7 @@ const WebApis = struct {
         @import("xhr/xhr.zig").Interfaces,
         @import("xhr/form_data.zig").Interfaces,
         @import("xmlserializer/xmlserializer.zig").Interfaces,
+        @import("webcomponents/webcomponents.zig").Interfaces,
     });
 };
 
diff --git a/src/browser/html/elements.zig b/src/browser/html/elements.zig
index 3ce70361d..948810a2a 100644
--- a/src/browser/html/elements.zig
+++ b/src/browser/html/elements.zig
@@ -16,6 +16,7 @@
 // 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 std = @import("std");
+const log = @import("../../log.zig");
 
 const parser = @import("../netsurf.zig");
 const generate = @import("../../runtime/generate.zig");
@@ -112,6 +113,10 @@ pub const HTMLElement = struct {
     pub const prototype = *Element;
     pub const subtype = .node;
 
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
+
     pub fn get_style(e: *parser.ElementHTML, page: *Page) !*CSSStyleDeclaration {
         const state = try page.getOrCreateNodeState(@ptrCast(e));
         return &state.style;
@@ -174,6 +179,10 @@ pub const HTMLMediaElement = struct {
     pub const Self = parser.MediaElement;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 // HTML elements
@@ -183,6 +192,10 @@ pub const HTMLUnknownElement = struct {
     pub const Self = parser.Unknown;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 // https://html.spec.whatwg.org/#the-a-element
@@ -191,6 +204,10 @@ pub const HTMLAnchorElement = struct {
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
 
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
+
     pub fn get_target(self: *parser.Anchor) ![]const u8 {
         return try parser.anchorGetTarget(self);
     }
@@ -428,144 +445,240 @@ pub const HTMLAppletElement = struct {
     pub const Self = parser.Applet;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLAreaElement = struct {
     pub const Self = parser.Area;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLAudioElement = struct {
     pub const Self = parser.Audio;
     pub const prototype = *HTMLMediaElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLBRElement = struct {
     pub const Self = parser.BR;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLBaseElement = struct {
     pub const Self = parser.Base;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLBodyElement = struct {
     pub const Self = parser.Body;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLButtonElement = struct {
     pub const Self = parser.Button;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLCanvasElement = struct {
     pub const Self = parser.Canvas;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLDListElement = struct {
     pub const Self = parser.DList;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLDataElement = struct {
     pub const Self = parser.Data;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLDataListElement = struct {
     pub const Self = parser.DataList;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLDialogElement = struct {
     pub const Self = parser.Dialog;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLDirectoryElement = struct {
     pub const Self = parser.Directory;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLDivElement = struct {
     pub const Self = parser.Div;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLEmbedElement = struct {
     pub const Self = parser.Embed;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLFieldSetElement = struct {
     pub const Self = parser.FieldSet;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLFontElement = struct {
     pub const Self = parser.Font;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLFrameElement = struct {
     pub const Self = parser.Frame;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLFrameSetElement = struct {
     pub const Self = parser.FrameSet;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLHRElement = struct {
     pub const Self = parser.HR;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLHeadElement = struct {
     pub const Self = parser.Head;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLHeadingElement = struct {
     pub const Self = parser.Heading;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLHtmlElement = struct {
     pub const Self = parser.Html;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLIFrameElement = struct {
     pub const Self = parser.IFrame;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLImageElement = struct {
@@ -573,6 +686,10 @@ pub const HTMLImageElement = struct {
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
 
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
+
     pub fn get_alt(self: *parser.Image) ![]const u8 {
         return try parser.imageGetAlt(self);
     }
@@ -613,6 +730,7 @@ pub const HTMLImageElement = struct {
     pub const Factory = struct {
         pub const js_name = "Image";
         pub const subtype = .node;
+
         pub const js_legacy_factory = true;
         pub const prototype = *HTMLImageElement;
 
@@ -631,6 +749,10 @@ pub const HTMLInputElement = struct {
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
 
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
+
     pub fn get_defaultValue(self: *parser.Input) ![]const u8 {
         return try parser.inputGetDefaultValue(self);
     }
@@ -719,114 +841,190 @@ pub const HTMLLIElement = struct {
     pub const Self = parser.LI;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLLabelElement = struct {
     pub const Self = parser.Label;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLLegendElement = struct {
     pub const Self = parser.Legend;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLLinkElement = struct {
     pub const Self = parser.Link;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLMapElement = struct {
     pub const Self = parser.Map;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLMetaElement = struct {
     pub const Self = parser.Meta;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLMeterElement = struct {
     pub const Self = parser.Meter;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLModElement = struct {
     pub const Self = parser.Mod;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLOListElement = struct {
     pub const Self = parser.OList;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLObjectElement = struct {
     pub const Self = parser.Object;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLOptGroupElement = struct {
     pub const Self = parser.OptGroup;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLOptionElement = struct {
     pub const Self = parser.Option;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLOutputElement = struct {
     pub const Self = parser.Output;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLParagraphElement = struct {
     pub const Self = parser.Paragraph;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLParamElement = struct {
     pub const Self = parser.Param;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLPictureElement = struct {
     pub const Self = parser.Picture;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLPreElement = struct {
     pub const Self = parser.Pre;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLProgressElement = struct {
     pub const Self = parser.Progress;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLQuoteElement = struct {
     pub const Self = parser.Quote;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 // https://html.spec.whatwg.org/#the-script-element
@@ -835,6 +1033,10 @@ pub const HTMLScriptElement = struct {
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
 
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
+
     pub fn get_src(self: *parser.Script) !?[]const u8 {
         return try parser.elementGetAttribute(
             parser.scriptToElt(self),
@@ -969,101 +1171,166 @@ pub const HTMLSourceElement = struct {
     pub const Self = parser.Source;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLSpanElement = struct {
     pub const Self = parser.Span;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLStyleElement = struct {
     pub const Self = parser.Style;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLTableElement = struct {
     pub const Self = parser.Table;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLTableCaptionElement = struct {
     pub const Self = parser.TableCaption;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLTableCellElement = struct {
     pub const Self = parser.TableCell;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLTableColElement = struct {
     pub const Self = parser.TableCol;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLTableRowElement = struct {
     pub const Self = parser.TableRow;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLTableSectionElement = struct {
     pub const Self = parser.TableSection;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLTemplateElement = struct {
     pub const Self = parser.Template;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLTextAreaElement = struct {
     pub const Self = parser.TextArea;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLTimeElement = struct {
     pub const Self = parser.Time;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLTitleElement = struct {
     pub const Self = parser.Title;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLTrackElement = struct {
     pub const Self = parser.Track;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLUListElement = struct {
     pub const Self = parser.UList;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub const HTMLVideoElement = struct {
     pub const Self = parser.Video;
     pub const prototype = *HTMLElement;
     pub const subtype = .node;
+
+    pub fn constructor(page: *Page, js_this: Env.JsThis) !*parser.Element {
+        return constructHtmlElement(page, js_this);
+    }
 };
 
 pub fn toInterface(comptime T: type, e: *parser.Element) !T {
     const elem: *align(@alignOf(*parser.Element)) parser.Element = @alignCast(e);
     const tag = try parser.elementHTMLGetTagType(@as(*parser.ElementHTML, @ptrCast(elem)));
+
     return switch (tag) {
         .abbr, .acronym, .address, .article, .aside, .b, .basefont, .bdi, .bdo, .bgsound, .big, .center, .cite, .code, .dd, .details, .dfn, .dt, .em, .figcaption, .figure, .footer, .header, .hgroup, .i, .isindex, .keygen, .kbd, .main, .mark, .marquee, .menu, .menuitem, .nav, .nobr, .noframes, .noscript, .rp, .rt, .ruby, .s, .samp, .section, .small, .spacer, .strike, .strong, .sub, .summary, .sup, .tt, .u, .wbr, ._var => .{ .HTMLElement = @as(*parser.ElementHTML, @ptrCast(elem)) },
         .a => .{ .HTMLAnchorElement = @as(*parser.Anchor, @ptrCast(elem)) },
@@ -1135,6 +1402,16 @@ pub fn toInterface(comptime T: type, e: *parser.Element) !T {
     };
 }
 
+fn constructHtmlElement(page: *Page, js_this: Env.JsThis) !*parser.Element {
+    const constructor_name = try js_this.constructorName(page.call_arena);
+    if (!page.window.custom_elements.lookup.contains(constructor_name)) {
+        return error.IllegalContructor;
+    }
+
+    const el = try parser.documentCreateElement(@ptrCast(page.window.document), constructor_name);
+    return el;
+}
+
 const testing = @import("../../testing.zig");
 test "Browser.HTML.Element" {
     var runner = try testing.jsRunner(testing.tracking_allocator, .{});
diff --git a/src/browser/html/window.zig b/src/browser/html/window.zig
index 02381971c..74fa28b3d 100644
--- a/src/browser/html/window.zig
+++ b/src/browser/html/window.zig
@@ -33,6 +33,7 @@ const EventTarget = @import("../dom/event_target.zig").EventTarget;
 const MediaQueryList = @import("media_query_list.zig").MediaQueryList;
 const Performance = @import("performance.zig").Performance;
 const CSSStyleDeclaration = @import("../cssom/css_style_declaration.zig").CSSStyleDeclaration;
+const CustomElementRegistry = @import("../webcomponents/custom_element_registry.zig").CustomElementRegistry;
 
 const storage = @import("../storage/storage.zig");
 
@@ -58,6 +59,7 @@ pub const Window = struct {
     console: Console = .{},
     navigator: Navigator = .{},
     performance: Performance,
+    custom_elements: CustomElementRegistry = .{},
 
     pub fn create(target: ?[]const u8, navigator: ?Navigator) !Window {
         var fbs = std.io.fixedBufferStream("");
@@ -163,6 +165,10 @@ pub const Window = struct {
         return &self.performance;
     }
 
+    pub fn get_customElements(self: *Window) *CustomElementRegistry {
+        return &self.custom_elements;
+    }
+
     pub fn _requestAnimationFrame(self: *Window, cbk: Function, page: *Page) !u32 {
         return self.createTimeout(cbk, 5, page, .{ .animation_frame = true });
     }
@@ -337,20 +343,15 @@ test "Browser.HTML.Window" {
     // Note however that we in this test do not wait as the request is just send to the browser
     try runner.testCases(&.{
         .{
-            \\ let start;
+            \\ let start = 0;
             \\ function step(timestamp) {
-            \\    if (start === undefined) {
-            \\      start = timestamp;
-            \\    }
-            \\    const elapsed = timestamp - start;
-            \\    if (elapsed < 2000) {
-            \\      requestAnimationFrame(step);
-            \\    }
+            \\    start = timestamp;
             \\ }
             ,
             null,
         },
         .{ "requestAnimationFrame(step);", null }, // returned id is checked in the next test
+        .{ " start > 0", "true" },
     }, .{});
 
     // cancelAnimationFrame should be able to cancel a request with the given id
diff --git a/src/browser/page.zig b/src/browser/page.zig
index 396022dba..368a3c5a7 100644
--- a/src/browser/page.zig
+++ b/src/browser/page.zig
@@ -352,8 +352,23 @@ pub const Page = struct {
                 continue;
             }
 
-            const e = parser.nodeToElement(next.?);
+            const current = next.?;
+
+            const e = parser.nodeToElement(current);
             const tag = try parser.elementHTMLGetTagType(@as(*parser.ElementHTML, @ptrCast(e)));
+
+            // if (tag == .undef) {
+            //     const tag_name = try parser.nodeLocalName(@ptrCast(e));
+            //     const custom_elements = &self.window.custom_elements;
+            //     if (custom_elements._get(tag_name)) |construct| {
+            //         try construct.printFunc();
+            //         // This is just here for testing for now.
+            //         // var result: Env.Function.Result = undefined;
+            //         // _ = try construct.newInstance(*parser.Element, &result);
+            //         log.info(.browser, "Registered WebComponent Found", .{ .element_name = tag_name });
+            //     }
+            // }
+
             if (tag != .script) {
                 // ignore non-js script.
                 continue;
diff --git a/src/browser/webcomponents/custom_element_registry.zig b/src/browser/webcomponents/custom_element_registry.zig
new file mode 100644
index 000000000..3e429a67c
--- /dev/null
+++ b/src/browser/webcomponents/custom_element_registry.zig
@@ -0,0 +1,91 @@
+// Copyright (C) 2023-2024  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 std = @import("std");
+const log = @import("../../log.zig");
+const v8 = @import("v8");
+
+const Env = @import("../env.zig").Env;
+const Page = @import("../page.zig").Page;
+
+const Element = @import("../dom/element.zig").Element;
+
+pub const CustomElementRegistry = struct {
+    // tag_name -> Function
+    lookup: std.StringHashMapUnmanaged(Env.Function) = .empty,
+
+    pub fn _define(self: *CustomElementRegistry, tag_name: []const u8, fun: Env.Function, page: *Page) !void {
+        log.info(.browser, "define custom element", .{ .name = tag_name });
+
+        const arena = page.arena;
+        const gop = try self.lookup.getOrPut(arena, tag_name);
+        if (!gop.found_existing) {
+            errdefer _ = self.lookup.remove(tag_name);
+            const owned_tag_name = try arena.dupe(u8, tag_name);
+            gop.key_ptr.* = owned_tag_name;
+        }
+        gop.value_ptr.* = fun;
+        fun.setName(tag_name);
+    }
+
+    pub fn _get(self: *CustomElementRegistry, name: []const u8) ?Env.Function {
+        return self.lookup.get(name);
+    }
+};
+
+const testing = @import("../../testing.zig");
+
+test "Browser.CustomElementRegistry" {
+    var runner = try testing.jsRunner(testing.tracking_allocator, .{});
+    defer runner.deinit();
+    try runner.testCases(&.{
+        // Basic registry access
+        .{ "typeof customElements", "object" },
+        .{ "customElements instanceof CustomElementRegistry", "true" },
+
+        // Define a simple custom element
+        .{
+            \\ class MyElement extends HTMLElement {
+            \\   constructor() {
+            \\      super();
+            \\      this.textContent = 'Hello World';
+            \\   }
+            \\ }
+            ,
+            null,
+        },
+        .{ "customElements.define('my-element', MyElement)", "undefined" },
+
+        // Check if element is defined
+        .{ "customElements.get('my-element') === MyElement", "true" },
+        // .{ "customElements.get('non-existent')", "null" },
+
+        // Create element via document.createElement
+        .{ "let el = document.createElement('my-element')", "undefined" },
+        .{ "el instanceof MyElement", "true" },
+        .{ "el instanceof HTMLElement", "true" },
+        .{ "el.tagName", "MY-ELEMENT" },
+        .{ "el.textContent", "Hello World" },
+
+        // Create element via HTML parsing
+        // .{ "document.body.innerHTML = '<my-element></my-element>'", "undefined" },
+        // .{ "let parsed = document.querySelector('my-element')", "undefined" },
+        // .{ "parsed instanceof MyElement", "true" },
+        // .{ "parsed.textContent", "Hello World" },
+    }, .{});
+}
diff --git a/src/browser/webcomponents/webcomponents.zig b/src/browser/webcomponents/webcomponents.zig
new file mode 100644
index 000000000..2ba2a30fc
--- /dev/null
+++ b/src/browser/webcomponents/webcomponents.zig
@@ -0,0 +1,23 @@
+// Copyright (C) 2023-2024  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 CustomElementRegistry = @import("custom_element_registry.zig").CustomElementRegistry;
+
+pub const Interfaces = .{
+    CustomElementRegistry,
+};
diff --git a/src/browser/xhr/form_data.zig b/src/browser/xhr/form_data.zig
index 485ef6479..48e03ad37 100644
--- a/src/browser/xhr/form_data.zig
+++ b/src/browser/xhr/form_data.zig
@@ -115,17 +115,24 @@ const EntryIterable = iterator.Iterable(kv.EntryIterator, "FormDataEntryIterator
 // TODO: handle disabled fieldsets
 fn collectForm(form: *parser.Form, submitter_: ?*parser.ElementHTML, page: *Page) !kv.List {
     const arena = page.arena;
-    const collection = try parser.formGetCollection(form);
-    const len = try parser.htmlCollectionGetLength(collection);
+
+    // Don't use libdom's formGetCollection (aka dom_html_form_element_get_elements)
+    // It doesn't work with dynamically added elements, because their form
+    // property doesn't get set. We should fix that.
+    // However, even once fixed, there are other form-collection features we
+    // probably want to implement (like disabled fieldsets), so we might want
+    // to stick with our own walker even if fix libdom to properly support
+    // dynamically added elements.
+    const node_list = try @import("../dom/css.zig").querySelectorAll(arena, @alignCast(@ptrCast(form)), "input,select,button,textarea");
+    const nodes = node_list.nodes.items;
 
     var entries: kv.List = .{};
-    try entries.ensureTotalCapacity(arena, len);
+    try entries.ensureTotalCapacity(arena, nodes.len);
 
     var submitter_included = false;
     const submitter_name_ = try getSubmitterName(submitter_);
 
-    for (0..len) |i| {
-        const node = try parser.htmlCollectionItem(collection, @intCast(i));
+    for (nodes) |node| {
         const element = parser.nodeToElement(node);
 
         // must have a name
@@ -181,10 +188,7 @@ fn collectForm(form: *parser.Form, submitter_: ?*parser.ElementHTML, page: *Page
                     submitter_included = true;
                 }
             },
-            else => {
-                log.warn(.web_api, "unsupported form element", .{ .tag = @tagName(tag) });
-                continue;
-            },
+            else => unreachable,
         }
     }
 
@@ -297,6 +301,7 @@ test "Browser.FormData" {
         \\   <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>
     });
     defer runner.deinit();
 
@@ -356,6 +361,8 @@ test "Browser.FormData" {
 
     try runner.testCases(&.{
         .{ "let form1 = document.getElementById('form1')", null },
+        .{ "let input = document.createElement('input');", null },
+        .{ "input.name = 'dyn'; input.value= 'dyn-v'; form1.appendChild(input);", null },
         .{ "let submit1 = document.getElementById('s1')", null },
         .{ "let f2 = new FormData(form1, submit1)", null },
         .{ "acc = '';", null },
@@ -378,6 +385,7 @@ test "Browser.FormData" {
             \\mlt-2=water
             \\mlt-2=tea
             \\s1=s1-v
+            \\dyn=dyn-v
         },
     }, .{});
 }
diff --git a/src/cdp/cdp.zig b/src/cdp/cdp.zig
index 3b0005f4a..30b05499d 100644
--- a/src/cdp/cdp.zig
+++ b/src/cdp/cdp.zig
@@ -23,7 +23,6 @@ const json = std.json;
 const log = @import("../log.zig");
 const App = @import("../app.zig").App;
 const Env = @import("../browser/env.zig").Env;
-const asUint = @import("../str/parser.zig").asUint;
 const Browser = @import("../browser/browser.zig").Browser;
 const Session = @import("../browser/session.zig").Session;
 const Page = @import("../browser/page.zig").Page;
@@ -182,41 +181,41 @@ pub fn CDPT(comptime TypeProvider: type) type {
 
             switch (domain.len) {
                 3 => switch (@as(u24, @bitCast(domain[0..3].*))) {
-                    asUint("DOM") => return @import("domains/dom.zig").processMessage(command),
-                    asUint("Log") => return @import("domains/log.zig").processMessage(command),
-                    asUint("CSS") => return @import("domains/css.zig").processMessage(command),
+                    asUint(u24, "DOM") => return @import("domains/dom.zig").processMessage(command),
+                    asUint(u24, "Log") => return @import("domains/log.zig").processMessage(command),
+                    asUint(u24, "CSS") => return @import("domains/css.zig").processMessage(command),
                     else => {},
                 },
                 4 => switch (@as(u32, @bitCast(domain[0..4].*))) {
-                    asUint("Page") => return @import("domains/page.zig").processMessage(command),
+                    asUint(u32, "Page") => return @import("domains/page.zig").processMessage(command),
                     else => {},
                 },
                 5 => switch (@as(u40, @bitCast(domain[0..5].*))) {
-                    asUint("Fetch") => return @import("domains/fetch.zig").processMessage(command),
-                    asUint("Input") => return @import("domains/input.zig").processMessage(command),
+                    asUint(u40, "Fetch") => return @import("domains/fetch.zig").processMessage(command),
+                    asUint(u40, "Input") => return @import("domains/input.zig").processMessage(command),
                     else => {},
                 },
                 6 => switch (@as(u48, @bitCast(domain[0..6].*))) {
-                    asUint("Target") => return @import("domains/target.zig").processMessage(command),
+                    asUint(u48, "Target") => return @import("domains/target.zig").processMessage(command),
                     else => {},
                 },
                 7 => switch (@as(u56, @bitCast(domain[0..7].*))) {
-                    asUint("Browser") => return @import("domains/browser.zig").processMessage(command),
-                    asUint("Runtime") => return @import("domains/runtime.zig").processMessage(command),
-                    asUint("Network") => return @import("domains/network.zig").processMessage(command),
+                    asUint(u56, "Browser") => return @import("domains/browser.zig").processMessage(command),
+                    asUint(u56, "Runtime") => return @import("domains/runtime.zig").processMessage(command),
+                    asUint(u56, "Network") => return @import("domains/network.zig").processMessage(command),
                     else => {},
                 },
                 8 => switch (@as(u64, @bitCast(domain[0..8].*))) {
-                    asUint("Security") => return @import("domains/security.zig").processMessage(command),
+                    asUint(u64, "Security") => return @import("domains/security.zig").processMessage(command),
                     else => {},
                 },
                 9 => switch (@as(u72, @bitCast(domain[0..9].*))) {
-                    asUint("Emulation") => return @import("domains/emulation.zig").processMessage(command),
-                    asUint("Inspector") => return @import("domains/inspector.zig").processMessage(command),
+                    asUint(u72, "Emulation") => return @import("domains/emulation.zig").processMessage(command),
+                    asUint(u72, "Inspector") => return @import("domains/inspector.zig").processMessage(command),
                     else => {},
                 },
                 11 => switch (@as(u88, @bitCast(domain[0..11].*))) {
-                    asUint("Performance") => return @import("domains/performance.zig").processMessage(command),
+                    asUint(u88, "Performance") => return @import("domains/performance.zig").processMessage(command),
                     else => {},
                 },
                 else => {},
@@ -696,6 +695,10 @@ const InputParams = struct {
     }
 };
 
+fn asUint(comptime T: type, comptime string: []const u8) T {
+    return @bitCast(string[0..string.len].*);
+}
+
 const testing = @import("testing.zig");
 test "cdp: invalid json" {
     var ctx = testing.context();
diff --git a/src/http/client.zig b/src/http/client.zig
index c6cf71c02..385e8e0ad 100644
--- a/src/http/client.zig
+++ b/src/http/client.zig
@@ -3170,7 +3170,7 @@ test "HttpClient: async tls no body" {
     }
 }
 
-test "HttpClient: async tls with body x" {
+test "HttpClient: async tls with body" {
     defer testing.reset();
     for (0..5) |_| {
         var client = try testClient();
diff --git a/src/log.zig b/src/log.zig
index 93df4c481..e00621ee7 100644
--- a/src/log.zig
+++ b/src/log.zig
@@ -146,6 +146,16 @@ fn logTo(comptime scope: Scope, level: Level, comptime msg: []const u8, data: an
 }
 
 fn logLogfmt(comptime scope: Scope, level: Level, comptime msg: []const u8, data: anytype, writer: anytype) !void {
+    try logLogFmtPrefix(scope, level, msg, writer);
+    inline for (@typeInfo(@TypeOf(data)).@"struct".fields) |f| {
+        const key = " " ++ f.name ++ "=";
+        try writer.writeAll(key);
+        try writeValue(.logfmt, @field(data, f.name), writer);
+    }
+    try writer.writeByte('\n');
+}
+
+fn logLogFmtPrefix(comptime scope: Scope, level: Level, comptime msg: []const u8, writer: anytype) !void {
     try writer.writeAll("$time=");
     try writer.print("{d}", .{timestamp()});
 
@@ -164,15 +174,20 @@ fn logLogfmt(comptime scope: Scope, level: Level, comptime msg: []const u8, data
         break :blk prefix ++ "\"" ++ msg ++ "\"";
     };
     try writer.writeAll(full_msg);
+}
+
+fn logPretty(comptime scope: Scope, level: Level, comptime msg: []const u8, data: anytype, writer: anytype) !void {
+    try logPrettyPrefix(scope, level, msg, writer);
     inline for (@typeInfo(@TypeOf(data)).@"struct".fields) |f| {
-        const key = " " ++ f.name ++ "=";
+        const key = "      " ++ f.name ++ " = ";
         try writer.writeAll(key);
-        try writeValue(.logfmt, @field(data, f.name), writer);
+        try writeValue(.pretty, @field(data, f.name), writer);
+        try writer.writeByte('\n');
     }
     try writer.writeByte('\n');
 }
 
-fn logPretty(comptime scope: Scope, level: Level, comptime msg: []const u8, data: anytype, writer: anytype) !void {
+fn logPrettyPrefix(comptime scope: Scope, level: Level, comptime msg: []const u8, writer: anytype) !void {
     if (scope == .console and level == .fatal and comptime std.mem.eql(u8, msg, "lightpanda")) {
         try writer.writeAll("\x1b[0;104mWARN  ");
     } else {
@@ -201,14 +216,6 @@ fn logPretty(comptime scope: Scope, level: Level, comptime msg: []const u8, data
         try writer.print(" \x1b[0m[+{d}ms]", .{elapsed()});
         try writer.writeByte('\n');
     }
-
-    inline for (@typeInfo(@TypeOf(data)).@"struct".fields) |f| {
-        const key = "      " ++ f.name ++ " = ";
-        try writer.writeAll(key);
-        try writeValue(.pretty, @field(data, f.name), writer);
-        try writer.writeByte('\n');
-    }
-    try writer.writeByte('\n');
 }
 
 pub fn writeValue(comptime format: Format, value: anytype, writer: anytype) !void {
diff --git a/src/runtime/js.zig b/src/runtime/js.zig
index 86619c6a4..083b86e3b 100644
--- a/src/runtime/js.zig
+++ b/src/runtime/js.zig
@@ -1158,7 +1158,7 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                             }
 
                             if (!js_value.isArray()) {
-                                return error.InvalidArgument;
+                                return .{.invalid = {}};
                             }
 
                             // This can get tricky.
@@ -1257,6 +1257,16 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                 exception: []const u8,
             };
 
+            pub fn getName(self: *const Function, allocator: Allocator) ![]const u8 {
+                const name = self.func.castToFunction().getName();
+                return valueToString(allocator, name, self.js_context.isolate, self.js_context.v8_context);
+            }
+
+            pub fn setName(self: *const Function, name: []const u8) void {
+                const v8_name = v8.String.initUtf8(self.js_context.isolate, name);
+                self.func.castToFunction().setName(v8_name);
+            }
+
             pub fn withThis(self: *const Function, value: anytype) !Function {
                 const this_obj = if (@TypeOf(value) == JsObject)
                     value.js_obj
@@ -1271,6 +1281,33 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                 };
             }
 
+            pub fn newInstance(self: *const Function, result: *Result) !JsObject {
+                const context = self.js_context;
+
+                var try_catch: TryCatch = undefined;
+                try_catch.init(context);
+                defer try_catch.deinit();
+
+                // This creates a new instance using this Function as a constructor.
+                // This returns a generic Object
+                const js_obj = self.func.castToFunction().initInstance(context.v8_context, &.{}) orelse {
+                    if (try_catch.hasCaught()) {
+                        const allocator = context.call_arena;
+                        result.stack = try_catch.stack(allocator) catch null;
+                        result.exception = (try_catch.exception(allocator) catch "???") orelse "???";
+                    } else {
+                        result.stack = null;
+                        result.exception = "???";
+                    }
+                    return error.JsConstructorFailed;
+                };
+
+                return .{
+                    .js_context = context,
+                    .js_obj = js_obj,
+                };
+            }
+
             pub fn call(self: *const Function, comptime T: type, args: anytype) !T {
                 return self.callWithThis(T, self.getThis(), args);
             }
@@ -1450,6 +1487,11 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                     .js_obj = array.castTo(v8.Object),
                 };
             }
+
+            pub fn constructorName(self: JsObject, allocator: Allocator) ![]const u8 {
+                const str = try self.js_obj.getConstructorName();
+                return jsStringToZig(allocator, str, self.js_context.isolate);
+            }
         };
 
         // This only exists so that we know whether a function wants the opaque
@@ -1472,6 +1514,10 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
             pub fn set(self: JsThis, key: []const u8, value: anytype, opts: JsObject.SetOpts) !void {
                 return self.obj.set(key, value, opts);
             }
+
+            pub fn constructorName(self: JsThis, allocator: Allocator) ![]const u8 {
+                return try self.obj.constructorName(allocator);
+            }
         };
 
         pub const TryCatch = struct {
@@ -1784,7 +1830,7 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                     // a constructor function, we'll return an error.
                     if (@hasDecl(Struct, "constructor") == false) {
                         const iso = caller.isolate;
-                        const js_exception = iso.throwException(createException(iso, "illegal constructor"));
+                        const js_exception = iso.throwException(createException(iso, "Illegal Constructor"));
                         info.getReturnValue().set(js_exception);
                         return;
                     }
@@ -1876,7 +1922,7 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
                     defer caller.deinit();
 
                     const named_function = comptime NamedFunction.init(Struct, "get_" ++ name);
-                    caller.getter(Struct, named_function, info) catch |err| {
+                    caller.method(Struct, named_function, info) catch |err| {
                         caller.handleError(Struct, named_function, err, info);
                     };
                 }
@@ -1891,13 +1937,13 @@ pub fn Env(comptime State: type, comptime WebApis: type) type {
             const setter_callback = v8.FunctionTemplate.initCallback(isolate, struct {
                 fn callback(raw_info: ?*const v8.C_FunctionCallbackInfo) callconv(.c) void {
                     const info = v8.FunctionCallbackInfo.initFromV8(raw_info);
+                    std.debug.assert(info.length() == 1);
+
                     var caller = Caller(Self, State).init(info);
                     defer caller.deinit();
 
-                    std.debug.assert(info.length() == 1);
-                    const js_value = info.getArg(0);
                     const named_function = comptime NamedFunction.init(Struct, "set_" ++ name);
-                    caller.setter(Struct, named_function, js_value, info) catch |err| {
+                    caller.method(Struct, named_function, info) catch |err| {
                         caller.handleError(Struct, named_function, err, info);
                     };
                 }
@@ -2424,66 +2470,6 @@ fn Caller(comptime E: type, comptime State: type) type {
             info.getReturnValue().set(try js_context.zigValueToJs(res));
         }
 
-        fn getter(self: *Self, comptime Struct: type, comptime named_function: NamedFunction, info: v8.FunctionCallbackInfo) !void {
-            const js_context = self.js_context;
-            const func = @field(Struct, named_function.name);
-            const Getter = @TypeOf(func);
-            if (@typeInfo(Getter).@"fn".return_type == null) {
-                @compileError(@typeName(Struct) ++ " has a getter without a return type: " ++ @typeName(Getter));
-            }
-
-            var args: ParamterTypes(Getter) = undefined;
-            const arg_fields = @typeInfo(@TypeOf(args)).@"struct".fields;
-            switch (arg_fields.len) {
-                0 => {}, // getters _can_ be parameterless
-                1, 2 => {
-                    const zig_instance = try E.typeTaggedAnyOpaque(named_function, *Receiver(Struct), info.getThis());
-                    comptime assertSelfReceiver(Struct, named_function);
-                    @field(args, "0") = zig_instance;
-                    if (comptime arg_fields.len == 2) {
-                        comptime assertIsStateArg(Struct, named_function, 1);
-                        @field(args, "1") = js_context.state;
-                    }
-                },
-                else => @compileError(named_function.full_name + " has too many parmaters: " ++ @typeName(named_function.func)),
-            }
-            const res = @call(.auto, func, args);
-            info.getReturnValue().set(try js_context.zigValueToJs(res));
-        }
-
-        fn setter(self: *Self, comptime Struct: type, comptime named_function: NamedFunction, js_value: v8.Value, info: v8.FunctionCallbackInfo) !void {
-            const js_context = self.js_context;
-            const func = @field(Struct, named_function.name);
-            comptime assertSelfReceiver(Struct, named_function);
-
-            const zig_instance = try E.typeTaggedAnyOpaque(named_function, *Receiver(Struct), info.getThis());
-
-            const Setter = @TypeOf(func);
-            var args: ParamterTypes(Setter) = undefined;
-            const arg_fields = @typeInfo(@TypeOf(args)).@"struct".fields;
-            switch (arg_fields.len) {
-                0 => unreachable, // assertSelfReceiver make sure of this
-                1 => @compileError(named_function.full_name ++ " only has 1 parameter"),
-                2, 3 => {
-                    @field(args, "0") = zig_instance;
-                    @field(args, "1") = try js_context.jsValueToZig(named_function, arg_fields[1].type, js_value);
-                    if (comptime arg_fields.len == 3) {
-                        comptime assertIsStateArg(Struct, named_function, 2);
-                        @field(args, "2") = js_context.state;
-                    }
-                },
-                else => @compileError(named_function.full_name ++ " setter with more than 3 parameters, why?"),
-            }
-
-            if (@typeInfo(Setter).@"fn".return_type) |return_type| {
-                if (@typeInfo(return_type) == .error_union) {
-                    _ = try @call(.auto, func, args);
-                    return;
-                }
-            }
-            _ = @call(.auto, func, args);
-        }
-
         fn getIndex(self: *Self, comptime Struct: type, comptime named_function: NamedFunction, idx: u32, info: v8.PropertyCallbackInfo) !u8 {
             const js_context = self.js_context;
             const func = @field(Struct, named_function.name);
@@ -2596,19 +2582,14 @@ fn Caller(comptime E: type, comptime State: type) type {
 
             if (comptime builtin.mode == .Debug and @hasDecl(@TypeOf(info), "length")) {
                 if (log.enabled(.js, .warn)) {
-                    const args_dump = self.serializeFunctionArgs(info) catch "failed to serialize args";
-                    log.warn(.js, "function call error", .{
-                        .name = named_function.full_name,
-                        .err = err,
-                        .args = args_dump,
-                        .stack = stackForLogs(self.call_arena, isolate) catch |err1| @errorName(err1),
-                    });
+                    logFunctionCallError(self.call_arena, self.isolate, self.v8_context, err, named_function.full_name, info);
                 }
             }
 
             var js_err: ?v8.Value = switch (err) {
                 error.InvalidArgument => createTypeException(isolate, "invalid argument"),
                 error.OutOfMemory => createException(isolate, "out of memory"),
+                error.IllegalConstructor => createException(isolate, "Illegal Contructor"),
                 else => blk: {
                     const func = @field(Struct, named_function.name);
                     const return_type = @typeInfo(@TypeOf(func)).@"fn".return_type orelse {
@@ -2670,6 +2651,7 @@ fn Caller(comptime E: type, comptime State: type) type {
         // Does the error we want to return belong to the custom exeception's ErrorSet
         fn isErrorSetException(comptime Exception: type, err: anytype) bool {
             const Entry = std.meta.Tuple(&.{ []const u8, void });
+
             const error_set = @typeInfo(Exception.ErrorSet).error_set.?;
             const entries = comptime blk: {
                 var kv: [error_set.len]Entry = undefined;
@@ -2721,8 +2703,8 @@ fn Caller(comptime E: type, comptime State: type) type {
                 // a JS argument
                 if (comptime isJsThis(params[params.len - 1].type.?)) {
                     @field(args, std.fmt.comptimePrint("{d}", .{params.len - 1 + offset})) = .{ .obj = .{
+                        .js_context = js_context,
                         .js_obj = info.getThis(),
-                        .executor = self.executor,
                     } };
 
                     // AND the 2nd last parameter is state
@@ -2808,28 +2790,6 @@ fn Caller(comptime E: type, comptime State: type) type {
             const Const_State = if (ti == .pointer) *const ti.pointer.child else State;
             return T == State or T == Const_State;
         }
-
-        fn serializeFunctionArgs(self: *const Self, info: anytype) ![]const u8 {
-            const isolate = self.isolate;
-            const v8_context = self.v8_context;
-            const arena = self.call_arena;
-            const separator = log.separator();
-            const js_parameter_count = info.length();
-
-            var arr: std.ArrayListUnmanaged(u8) = .{};
-            for (0..js_parameter_count) |i| {
-                const js_value = info.getArg(@intCast(i));
-                const value_string = try valueToDetailString(arena, js_value, isolate, v8_context);
-                const value_type = try jsStringToZig(arena, try js_value.typeOf(isolate), isolate);
-                try std.fmt.format(arr.writer(arena), "{s}{d}: {s} ({s})", .{
-                    separator,
-                    i + 1,
-                    value_string,
-                    value_type,
-                });
-            }
-            return arr.items;
-        }
     };
 }
 
@@ -3270,6 +3230,37 @@ const NamedFunction = struct {
     }
 };
 
+// This is extracted to speed up compilation. When left inlined in handleError,
+// this can add as much as 10 seconds of compilation time.
+fn logFunctionCallError(arena: Allocator, isolate: v8.Isolate, context: v8.Context, err: anyerror, function_name: []const u8, info: v8.FunctionCallbackInfo) void {
+    const args_dump = serializeFunctionArgs(arena, isolate, context, info) catch "failed to serialize args";
+    log.warn(.js, "function call error", .{
+        .name = function_name,
+        .err = err,
+        .args = args_dump,
+        .stack = stackForLogs(arena, isolate) catch |err1| @errorName(err1),
+    });
+}
+
+fn serializeFunctionArgs(arena: Allocator, isolate: v8.Isolate, context: v8.Context, info: v8.FunctionCallbackInfo) ![]const u8 {
+    const separator = log.separator();
+    const js_parameter_count = info.length();
+
+    var arr: std.ArrayListUnmanaged(u8) = .{};
+    for (0..js_parameter_count) |i| {
+        const js_value = info.getArg(@intCast(i));
+        const value_string = try valueToDetailString(arena, js_value, isolate, context);
+        const value_type = try jsStringToZig(arena, try js_value.typeOf(isolate), isolate);
+        try std.fmt.format(arr.writer(arena), "{s}{d}: {s} ({s})", .{
+            separator,
+            i + 1,
+            value_string,
+            value_type,
+        });
+    }
+    return arr.items;
+}
+
 // This is called from V8. Whenever the v8 inspector has to describe a value
 // it'll call this function to gets its [optional] subtype - which, from V8's
 // point of view, is an arbitrary string.
diff --git a/src/str/parser.zig b/src/str/parser.zig
deleted file mode 100644
index b2429f818..000000000
--- a/src/str/parser.zig
+++ /dev/null
@@ -1,125 +0,0 @@
-// Copyright (C) 2023-2024  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/>.
-
-// some utils to parser strings.
-const std = @import("std");
-
-pub const Reader = struct {
-    pos: usize = 0,
-    data: []const u8,
-
-    pub fn until(self: *Reader, c: u8) []const u8 {
-        const pos = self.pos;
-        const data = self.data;
-
-        const index = std.mem.indexOfScalarPos(u8, data, pos, c) orelse data.len;
-        self.pos = index;
-        return data[pos..index];
-    }
-
-    pub fn tail(self: *Reader) []const u8 {
-        const pos = self.pos;
-        const data = self.data;
-        if (pos > data.len) {
-            return "";
-        }
-        self.pos = data.len;
-        return data[pos..];
-    }
-
-    pub fn skip(self: *Reader) bool {
-        const pos = self.pos;
-        if (pos >= self.data.len) {
-            return false;
-        }
-        self.pos = pos + 1;
-        return true;
-    }
-};
-
-// converts a comptime-known string (i.e. null terminated) to an uint
-pub fn asUint(comptime string: anytype) AsUintReturn(string) {
-    const byteLength = @bitSizeOf(@TypeOf(string.*)) / 8 - 1;
-    const expectedType = *const [byteLength:0]u8;
-    if (@TypeOf(string) != expectedType) {
-        @compileError("expected : " ++ @typeName(expectedType) ++
-            ", got: " ++ @typeName(@TypeOf(string)));
-    }
-
-    return @bitCast(@as(*const [byteLength]u8, string).*);
-}
-
-fn AsUintReturn(comptime string: anytype) type {
-    return @Type(.{
-        .int = .{
-            .bits = @bitSizeOf(@TypeOf(string.*)) - 8, // (- 8) to exclude sentinel 0
-            .signedness = .unsigned,
-        },
-    });
-}
-
-const testing = std.testing;
-test "parser.Reader: skip" {
-    var r = Reader{ .data = "foo" };
-    try testing.expectEqual(true, r.skip());
-    try testing.expectEqual(true, r.skip());
-    try testing.expectEqual(true, r.skip());
-    try testing.expectEqual(false, r.skip());
-    try testing.expectEqual(false, r.skip());
-}
-
-test "parser.Reader: tail" {
-    var r = Reader{ .data = "foo" };
-    try testing.expectEqualStrings("foo", r.tail());
-    try testing.expectEqualStrings("", r.tail());
-    try testing.expectEqualStrings("", r.tail());
-}
-
-test "parser.Reader: until" {
-    var r = Reader{ .data = "foo.bar.baz" };
-    try testing.expectEqualStrings("foo", r.until('.'));
-    _ = r.skip();
-    try testing.expectEqualStrings("bar", r.until('.'));
-    _ = r.skip();
-    try testing.expectEqualStrings("baz", r.until('.'));
-
-    r = Reader{ .data = "foo" };
-    try testing.expectEqualStrings("foo", r.until('.'));
-    try testing.expectEqualStrings("", r.tail());
-
-    r = Reader{ .data = "" };
-    try testing.expectEqualStrings("", r.until('.'));
-    try testing.expectEqualStrings("", r.tail());
-}
-
-test "parser: asUint" {
-    const ASCII_x = @as(u8, @bitCast([1]u8{'x'}));
-    const ASCII_ab = @as(u16, @bitCast([2]u8{ 'a', 'b' }));
-    const ASCII_xyz = @as(u24, @bitCast([3]u8{ 'x', 'y', 'z' }));
-    const ASCII_abcd = @as(u32, @bitCast([4]u8{ 'a', 'b', 'c', 'd' }));
-
-    try testing.expectEqual(ASCII_x, asUint("x"));
-    try testing.expectEqual(ASCII_ab, asUint("ab"));
-    try testing.expectEqual(ASCII_xyz, asUint("xyz"));
-    try testing.expectEqual(ASCII_abcd, asUint("abcd"));
-
-    try testing.expectEqual(u8, @TypeOf(asUint("x")));
-    try testing.expectEqual(u16, @TypeOf(asUint("ab")));
-    try testing.expectEqual(u24, @TypeOf(asUint("xyz")));
-    try testing.expectEqual(u32, @TypeOf(asUint("abcd")));
-}