custom-elements/parser/parser-sets-attributes-and-children.html

<!DOCTYPE html>
<html>
<head>
<title>Custom Elements: Changes to the HTML parser</title>
<meta name="author" title="Ryosuke Niwa" href="mailto:rniwa@webkit.org">
<meta name="assert" content="HTML parser must set the attributes and append the children on a custom element">
<link rel="help" href="https://html.spec.whatwg.org/#create-an-element-for-the-token">
<link rel="help" href="https://html.spec.whatwg.org/multipage/parsing.html#insert-a-foreign-element">
<link rel="help" href="https://dom.spec.whatwg.org/#concept-create-element">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="../resources/custom-elements-helpers.js"></script>
</head>
<body>
<div id="log"></div>
<script>

var numberOfAttributesInConstructor = 0;
var numberOfChildNodesInConstructor = 0;
var numberOfChildNodesInAttributeChangedCallback = 0;
var numberOfChildNodesInConnectedCallback = 0;
var attributesChangedCalls = [];

class MyCustomElement extends HTMLElement {
    constructor(...args) {
        super(...args);
        numberOfAttributesInConstructor = this.attributes.length;
        numberOfChildNodesInConstructor = this.childNodes.length;
    }

    attributeChangedCallback(...args) {
        attributesChangedCalls.push(create_attribute_changed_callback_log(this, ...args));
        numberOfChildNodesInAttributeChangedCallback = this.childNodes.length;
    }

    static get observedAttributes() {
        return ['id', 'class'];
    }

    connectedCallback() {
        numberOfChildNodesInConnectedCallback = this.childNodes.length;
    }
};
customElements.define('my-custom-element', MyCustomElement);

</script>
<my-custom-element id="custom-element-id" class="class1 class2">hello <b>world</b></my-custom-element>
<script>

var customElement = document.querySelector('my-custom-element');

test(function () {
    assert_equals(customElement.getAttribute('id'), 'custom-element-id', 'HTML parser must preserve the id attribute');
    assert_equals(customElement.id, 'custom-element-id', 'HTML parser must preserve the semantics of reflect for the id attribute');
    assert_equals(customElement.getAttribute('class'), 'class1 class2', 'HTML parser must preserve the class attribute');
    assert_equals(customElement.classList.length, 2, 'HTML parser must initialize classList on custom elements');
    assert_equals(customElement.classList[0], 'class1', 'HTML parser must initialize classList on custom elements');
    assert_equals(customElement.classList[1], 'class2', 'HTML parser must initialize classList on custom elements');
}, 'HTML parser must set the attributes');

test(function () {
    assert_equals(customElement.childNodes.length, 2, 'HTML parser must append child nodes');
    assert_true(customElement.firstChild instanceof Text, 'HTML parser must append Text node child to a custom element');
    assert_equals(customElement.firstChild.data, 'hello ', 'HTML parser must append Text node child to a custom element');
    assert_true(customElement.lastChild instanceof HTMLElement, 'HTML parser must append a builtin element child to a custom element');
    assert_true(customElement.lastChild.firstChild instanceof Text, 'HTML parser must preserve grandchild nodes of a custom element');
    assert_equals(customElement.lastChild.firstChild.data, 'world', 'HTML parser must preserve grandchild nodes of a custom element');
}, 'HTML parser must append child nodes');

test(function () {
    assert_equals(numberOfAttributesInConstructor, 0, 'HTML parser must not set attributes on a custom element before invoking the constructor');
    assert_equals(numberOfChildNodesInConstructor, 0, 'HTML parser must not append child nodes to a custom element before invoking the constructor');
}, 'HTML parser must set the attributes or append children before calling constructor');

test(function () {
    // https://html.spec.whatwg.org/multipage/parsing.html#insert-a-foreign-element
    // 3.3. Pop the element queue from the custom element reactions
    // stack, and invoke custom element reactions in that queue.
    assert_equals(numberOfChildNodesInConnectedCallback, 0);
}, 'HTML parser should call connectedCallback before appending child nodes.');

test(function () {
    assert_equals(attributesChangedCalls.length, 2);
    assert_attribute_log_entry(attributesChangedCalls[0], {name: 'id', oldValue: null, newValue: 'custom-element-id', namespace: null});
    assert_attribute_log_entry(attributesChangedCalls[1], {name: 'class', oldValue: null, newValue: 'class1 class2', namespace: null});
    // https://html.spec.whatwg.org/multipage/parsing.html#create-an-element-for-the-token
    // 9.2. Invoke custom element reactions in queue.
    assert_equals(numberOfChildNodesInAttributeChangedCallback, 0,
                  'attributeChangedCallback should be called ' +
                      'before appending a child');
}, 'HTML parser must enqueue attributeChanged reactions');

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