<!DOCTYPE html> <html> <head> <title>Custom Elements: Custom element reactions must be invoked before returning to author scripts</title> <meta name="author" title="Ryosuke Niwa" href="mailto:rniwa@webkit.org"> <meta name="assert" content="Custom element reactions must be invoked before returning to author scripts"> <link rel="help" href="https://html.spec.whatwg.org/multipage/scripting.html#invoke-custom-element-reactions"> <script src="/resources/testharness.js"></script> <script src="/resources/testharnessreport.js"></script> </head> <body> <div id="log"></div> <script> class MyCustomElement extends HTMLElement { attributeChangedCallback(...args) { this.handler(...args); } handler() { } } MyCustomElement.observedAttributes = ['data-title', 'title']; customElements.define('my-custom-element', MyCustomElement); test(function () { var instance = document.createElement('my-custom-element'); var anotherInstance = document.createElement('my-custom-element'); var callbackOrder = []; instance.handler = function () { callbackOrder.push([this, 'begin']); anotherInstance.setAttribute('data-title', 'baz'); callbackOrder.push([this, 'end']); } anotherInstance.handler = function () { callbackOrder.push([this, 'begin']); callbackOrder.push([this, 'end']); } instance.setAttribute('title', 'foo'); assert_equals(callbackOrder.length, 4); assert_array_equals(callbackOrder[0], [instance, 'begin']); assert_array_equals(callbackOrder[1], [anotherInstance, 'begin']); assert_array_equals(callbackOrder[2], [anotherInstance, 'end']); assert_array_equals(callbackOrder[3], [instance, 'end']); }, 'setAttribute and removeAttribute must enqueue and invoke attributeChangedCallback'); test(function () { var shouldCloneAnotherInstance = false; var anotherInstanceClone; var log = []; class SelfCloningElement extends HTMLElement { constructor() { super(); log.push([this, 'begin']); if (shouldCloneAnotherInstance) { shouldCloneAnotherInstance = false; anotherInstanceClone = anotherInstance.cloneNode(false); } log.push([this, 'end']); } } customElements.define('self-cloning-element', SelfCloningElement); var instance = document.createElement('self-cloning-element'); var anotherInstance = document.createElement('self-cloning-element'); shouldCloneAnotherInstance = true; assert_equals(log.length, 4); var instanceClone = instance.cloneNode(false); assert_equals(log.length, 8); assert_array_equals(log[0], [instance, 'begin']); assert_array_equals(log[1], [instance, 'end']); assert_array_equals(log[2], [anotherInstance, 'begin']); assert_array_equals(log[3], [anotherInstance, 'end']); assert_array_equals(log[4], [instanceClone, 'begin']); assert_array_equals(log[5], [anotherInstanceClone, 'begin']); assert_array_equals(log[6], [anotherInstanceClone, 'end']); assert_array_equals(log[7], [instanceClone, 'end']); }, 'Calling Node.prototype.cloneNode(false) must push a new element queue to the processing stack'); </script> </body> </html>