195403 2019-03-07 00:25:42 -0800 Customized built-in elements aren't supported 2019-12-27 09:03:39 -0800 1 1 1 Unclassified WebKit DOM WebKit Nightly Build All All RESOLVED DUPLICATE 182671 HTML5 P2 Major --- 1 andreas.deuschlinger webkit-unassigned arjunyel+webkit.bugzilla cdumez incoming-webkitbugs rniwa oldest_to_newest 1513440 0 andreas.deuschlinger 2019-03-07 00:25:42 -0800 The HTML Living Standard for Custom Elements specifies support to extend existing built-in elements, by: - the `is="my-button"` attribute https://html.spec.whatwg.org/multipage/custom-elements.html#attr-is - the `document.createElement('button', { is: 'my-button' })` second argument https://dom.spec.whatwg.org/#dom-elementcreationoptions-is Example: https://html.spec.whatwg.org/multipage/custom-elements.html#custom-elements-customized-builtin-example The Webkit Status page gives incorrect information claiming that Custom Elements V1 are supported, though in fact only "autonomous custom elements" are supported. https://webkit.org/status/#feature-custom-elements Caniuse informs about this incomplete implementation correctly: https://caniuse.com/#feat=custom-elementsv1 1514115 1 arjunyel+webkit.bugzilla 2019-03-08 11:53:01 -0800 Previous discussion about this on Github https://github.com/w3c/webcomponents/issues/509#issuecomment-222860736 1514452 2 rniwa 2019-03-09 18:24:45 -0800 Our position has been that this feature shouldn't exist in the spec in the first place. I really don't understand how we ended up allowing Google to keep this feature in the HTML5 spec despite of our repeated objections. *** This bug has been marked as a duplicate of bug 182671 *** 1515388 3 andreas.deuschlinger 2019-03-12 03:14:19 -0700 Thanks a lot for your quick feedback:) Meanwhile i came across element behaviors a the suggested has attributes: https://www.npmjs.com/package/element-behaviors Which is what I would really need:) But gies beyond this ticket...