custom-elements/parser/parser-constructs-custom-elements-with-is.html

<!DOCTYPE html>
<html>
<head>
<title>Custom Elements: Changes to the HTML parser</title>
<meta name="author" title="John Dai" href="mailto:jdai@mozilla.com">
<meta name="assert" content="HTML parser creates a custom element which contains is attribute">
<link rel="help" href="https://html.spec.whatwg.org/#create-an-element-for-the-token">
<link rel="help" href="https://dom.spec.whatwg.org/#concept-create-element">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
</head>
<body>
<div id="log"></div>
<autonomous-custom-element id="instance1" is="is-custom-element"></autonomous-custom-element>
<script>

class AutonomousCustomElement extends HTMLElement { };
class IsCustomElement extends HTMLElement { };

customElements.define('autonomous-custom-element', AutonomousCustomElement);
customElements.define('is-custom-element', IsCustomElement);

test(function () {
    var customElement = document.getElementById('instance1');

    assert_true(customElement instanceof HTMLElement, 'A resolved custom element must be an instance of HTMLElement');
    assert_false(customElement instanceof HTMLUnknownElement, 'A resolved custom element must NOT be an instance of HTMLUnknownElement');
    assert_true(customElement instanceof AutonomousCustomElement, 'A resolved custom element must be an instance of that custom element');
    assert_equals(customElement.localName, 'autonomous-custom-element');
    assert_equals(customElement.namespaceURI, 'http://www.w3.org/1999/xhtml', 'A custom element HTML must use HTML namespace');

}, 'HTML parser must create a defined autonomous custom element when customElements.define comes after HTML parser creation');

</script>
<autonomous-custom-element id="instance2" is="is-custom-element"></autonomous-custom-element>
<script>

test(function () {
    var customElement = document.getElementById('instance2');

    assert_true(customElement instanceof HTMLElement, 'A resolved custom element must be an instance of HTMLElement');
    assert_false(customElement instanceof HTMLUnknownElement, 'A resolved custom element must NOT be an instance of HTMLUnknownElement');
    assert_true(customElement instanceof AutonomousCustomElement, 'A resolved custom element must be an instance of that custom element');
    assert_equals(customElement.localName, 'autonomous-custom-element');
    assert_equals(customElement.namespaceURI, 'http://www.w3.org/1999/xhtml', 'A custom element HTML must use HTML namespace');

}, 'HTML parser must create a defined autonomous custom element when customElements.define comes before HTML parser creation');

</script>
</body>
</html>