<!DOCTYPE html> <title>Custom Elements: document.createElementNS should support custom elements</title> <link rel="help" content="https://dom.spec.whatwg.org/#concept-create-element"> <link rel="help" content="https://dom.spec.whatwg.org/#internal-createelementns-steps"> <script src="/resources/testharness.js"></script> <script src="/resources/testharnessreport.js"></script> <body> <script> test(() => { class MyBuiltinElement extends HTMLElement {}; customElements.define('my-builtin', MyBuiltinElement, { extends: 'address' }); let element = document.createElementNS('http://www.w3.org/1999/xhtml', 'p:address', { is: 'my-builtin'}); assert_true(element instanceof MyBuiltinElement); assert_equals(element.prefix, 'p'); assert_false(element.hasAttribute('is')); }, 'builtin: document.createElementNS should create custom elements with prefixes.'); test(() => { class MyBuiltinElement2 extends HTMLElement {}; customElements.define('my-builtin2', MyBuiltinElement2, { extends: 'address'}); let element = document.createElementNS('urn:example', 'address', { is: 'my-builtin2' }); assert_false(element instanceof MyBuiltinElement2); assert_false(element.hasAttribute('is')); }, 'builtin: document.createElementNS should check namespaces.'); test(() => { class SuperP extends HTMLParagraphElement {} customElements.define("super-p", SuperP, { extends: "p" }); const superP = document.createElementNS("http://www.w3.org/1999/xhtml", "p", { is: "super-p" }); assert_true(superP instanceof HTMLParagraphElement); assert_true(superP instanceof SuperP); assert_equals(superP.localName, "p"); const notSuperP = document.createElementNS("http://www.w3.org/1999/xhtml", "p", "super-p"); assert_true(notSuperP instanceof HTMLParagraphElement); assert_false(notSuperP instanceof SuperP); assert_equals(notSuperP.localName, "p"); }, "document.createElementNS()'s third argument is to be ignored when it's a string"); </script> </body>