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Test Info:
- This WPT test may be referenced by the following Test IDs:
- /custom-elements/HTMLElement-constructor.html - WPT Dashboard Interop Dashboard
<!DOCTYPE html>
<html>
<head>
<title>Custom Elements: HTMLElement must allow subclassing</title>
<meta name="author" title="Ryosuke Niwa" href="mailto:rniwa@webkit.org">
<meta name="assert" content="HTMLElement must allow subclassing">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
</head>
<body>
<div id="log"></div>
<script>
test(function () {
customElements.define('html-custom-element', HTMLElement);
assert_throws_js(TypeError, function () { new HTMLElement(); });
}, 'HTMLElement constructor must throw a TypeError when NewTarget is equal to itself');
test(function () {
customElements.define('html-proxy-custom-element', new Proxy(HTMLElement, {}));
assert_throws_js(TypeError, function () { new HTMLElement(); });
}, 'HTMLElement constructor must throw a TypeError when NewTarget is equal to itself via a Proxy object');
test(function () {
class SomeCustomElement extends HTMLElement {};
assert_throws_js(TypeError, function () { new SomeCustomElement; });
}, 'HTMLElement constructor must throw TypeError when it has not been defined by customElements.define');
test(function () {
class SomeCustomElement extends HTMLParagraphElement {};
customElements.define('some-custom-element', SomeCustomElement);
assert_throws_js(TypeError, function () { new SomeCustomElement(); });
}, 'Custom element constructor must throw TypeError when it does not extend HTMLElement');
test(function () {
class SomeCustomButtonElement extends HTMLButtonElement {};
customElements.define('some-custom-button-element', SomeCustomButtonElement, { extends: "p" });
assert_throws_js(TypeError, function () { new SomeCustomButtonElement(); });
}, 'Custom element constructor must throw TypeError when it does not extend the proper element interface');
test(function () {
class CustomElementWithInferredTagName extends HTMLElement {};
customElements.define('inferred-name', CustomElementWithInferredTagName);
var instance = new CustomElementWithInferredTagName;
assert_true(instance instanceof Element, 'A custom element must inherit from Element');
assert_true(instance instanceof Node, 'A custom element must inherit from Node');
assert_equals(instance.localName, 'inferred-name');
assert_equals(instance.nodeName, 'INFERRED-NAME');
assert_equals(instance.namespaceURI, 'http://www.w3.org/1999/xhtml', 'A custom HTML element must use HTML namespace');
document.body.appendChild(instance);
assert_equals(document.body.lastChild, instance,
'document.body.appendChild must be able to insert a custom element');
assert_equals(document.querySelector('inferred-name'), instance,
'document.querySelector must be able to find a custom element by its tag name');
}, 'HTMLElement constructor must infer the tag name from the element interface');
test(function () {
class ConcreteCustomElement extends HTMLElement { };
class SubCustomElement extends ConcreteCustomElement { };
customElements.define('concrete-custom-element', ConcreteCustomElement);
customElements.define('sub-custom-element', SubCustomElement);
var instance = new ConcreteCustomElement();
assert_true(instance instanceof ConcreteCustomElement);
assert_false(instance instanceof SubCustomElement);
assert_equals(instance.localName, 'concrete-custom-element');
assert_equals(instance.nodeName, 'CONCRETE-CUSTOM-ELEMENT');
var instance = new SubCustomElement();
assert_true(instance instanceof ConcreteCustomElement);
assert_true(instance instanceof SubCustomElement);
assert_equals(instance.localName, 'sub-custom-element');
assert_equals(instance.nodeName, 'SUB-CUSTOM-ELEMENT');
}, 'HTMLElement constructor must allow subclassing a custom element');
test(function () {
class AbstractCustomElement extends HTMLElement { };
class ConcreteSubCustomElement extends AbstractCustomElement { };
customElements.define('concrete-sub-custom-element', ConcreteSubCustomElement);
var instance = new ConcreteSubCustomElement();
assert_true(instance instanceof AbstractCustomElement);
assert_true(instance instanceof ConcreteSubCustomElement);
assert_equals(instance.localName, 'concrete-sub-custom-element');
assert_equals(instance.nodeName, 'CONCRETE-SUB-CUSTOM-ELEMENT');
}, 'HTMLElement constructor must allow subclassing an user-defined subclass of HTMLElement');
test(function() {
class SomeCustomElement extends HTMLElement {};
var getCount = 0;
var countingProxy = new Proxy(SomeCustomElement, {
get: function(target, prop, receiver) {
if (prop == "prototype") {
++getCount;
}
return Reflect.get(target, prop, receiver);
}
});
customElements.define("success-counting-element-1", countingProxy);
// define() gets the prototype of the constructor it's passed, so
// reset the counter.
getCount = 0;
var instance = new countingProxy();
assert_equals(getCount, 1, "Should have gotten .prototype once");
assert_true(instance instanceof countingProxy);
assert_true(instance instanceof HTMLElement);
assert_true(instance instanceof SomeCustomElement);
assert_equals(instance.localName, "success-counting-element-1");
assert_equals(instance.nodeName, "SUCCESS-COUNTING-ELEMENT-1");
}, 'HTMLElement constructor must only get .prototype once, calling proxy constructor directly');
test(function() {
class SomeCustomElement extends HTMLElement {};
var getCount = 0;
var countingProxy = new Proxy(SomeCustomElement, {
get: function(target, prop, receiver) {
if (prop == "prototype") {
++getCount;
}
return Reflect.get(target, prop, receiver);
}
});
customElements.define("success-counting-element-2", countingProxy);
// define() gets the prototype of the constructor it's passed, so
// reset the counter.
getCount = 0;
var instance = Reflect.construct(HTMLElement, [], countingProxy);
assert_equals(getCount, 1, "Should have gotten .prototype once");
assert_true(instance instanceof countingProxy);
assert_true(instance instanceof HTMLElement);
assert_true(instance instanceof SomeCustomElement);
assert_equals(instance.localName, "success-counting-element-2");
assert_equals(instance.nodeName, "SUCCESS-COUNTING-ELEMENT-2");
}, 'HTMLElement constructor must only get .prototype once, calling proxy constructor via Reflect');
test(function() {
class SomeCustomElement {};
var getCount = 0;
var countingProxy = new Proxy(SomeCustomElement, {
get: function(target, prop, receiver) {
if (prop == "prototype") {
++getCount;
}
return Reflect.get(target, prop, receiver);
}
});
customElements.define("success-counting-element-3", countingProxy);
// define() gets the prototype of the constructor it's passed, so
// reset the counter.
getCount = 0;
var instance = Reflect.construct(HTMLElement, [], countingProxy);
assert_equals(getCount, 1, "Should have gotten .prototype once");
assert_true(instance instanceof countingProxy);
assert_true(instance instanceof SomeCustomElement);
assert_equals(instance.localName, undefined);
assert_equals(instance.nodeName, undefined);
}, 'HTMLElement constructor must only get .prototype once, calling proxy constructor via Reflect with no inheritance');
test(function() {
class SomeCustomElement extends HTMLElement {};
var getCount = 0;
var countingProxy = new Proxy(SomeCustomElement, {
get: function(target, prop, receiver) {
if (prop == "prototype") {
++getCount;
}
return Reflect.get(target, prop, receiver);
}
});
// Purposefully don't register it.
assert_throws_js(TypeError,
function () { Reflect.construct(HTMLElement, [], countingProxy) },
"Should not be able to construct an HTMLElement named 'button'");
assert_equals(getCount, 0, "Should never have gotten .prototype");
}, 'HTMLElement constructor must not get .prototype until it finishes its registration sanity checks, calling via Reflect');
</script>
</body>
</html>