<!DOCTYPE HTML> <html> <!-- https://bugzilla.mozilla.org/show_bug.cgi?id=1275838 --> <head> <title>Test custom elements get function.</title> <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script> <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" /> </head> <body> <iframe id="iframe"></iframe> <a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1275838">Bug 1275838</a> <script> const testWindow = iframe.contentDocument.defaultView; const customElements = testWindow.customElements; ok('customElements' in testWindow, '"window.customElements" exists'); ok('define' in customElements, '"window.customElements.define" exists'); ok('get' in customElements, '"window.customElements.get" exists'); const name = 'test-get-existing'; class C extends HTMLElement {}; customElements.define(name, C); is(customElements.get(name), C, 'get() returns the constructor'); is(customElements.get('test-get-not-defined'), undefined, 'get() returns undefined for not-defined name'); </script> </body> </html>