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| /** | |
| * @license | |
| * Copyright (c) 2017 The Polymer Project Authors. All rights reserved. | |
| * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt | |
| * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt | |
| * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt | |
| * Code distributed by Google as part of the polymer project is also | |
| * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt | |
| */ | |
| (function() { | |
| 'use strict'; | |
| // global for (1) existence means `WebComponentsReady` will fire, | |
| // (2) WebComponents.ready == true means event has fired. | |
| window.WebComponents = window.WebComponents || {}; | |
| var name = 'webcomponents-loader.js'; | |
| // Feature detect which polyfill needs to be imported. | |
| var polyfills = []; | |
| if (!('import' in document.createElement('link'))) { | |
| polyfills.push('hi'); | |
| } | |
| if (!('attachShadow' in Element.prototype && 'getRootNode' in Element.prototype) || | |
| (window.ShadyDOM && window.ShadyDOM.force)) { | |
| polyfills.push('sd'); | |
| } | |
| if (!window.customElements || window.customElements.forcePolyfill) { | |
| polyfills.push('ce'); | |
| } | |
| var needsTemplate = (function() { | |
| // no real <template> because no `content` property (IE and older browsers) | |
| var t = document.createElement('template'); | |
| if (!('content' in t)) { | |
| return true; | |
| } | |
| // broken doc fragment (older Edge) | |
| if (!(t.content.cloneNode() instanceof DocumentFragment)) { | |
| return true; | |
| } | |
| // broken <template> cloning (Edge up to at least version 17) | |
| var t2 = document.createElement('template'); | |
| t2.content.appendChild(document.createElement('div')); | |
| t.content.appendChild(t2); | |
| var clone = t.cloneNode(true); | |
| return (clone.content.childNodes.length === 0 || | |
| clone.content.firstChild.content.childNodes.length === 0); | |
| })(); | |
| // NOTE: any browser that does not have template or ES6 features | |
| // must load the full suite (called `lite` for legacy reasons) of polyfills. | |
| if (!window.Promise || !Array.from || needsTemplate) { | |
| polyfills = ['lite']; | |
| } | |
| if (polyfills.length) { | |
| var script = document.querySelector('script[src*="' + name +'"]'); | |
| var newScript = document.createElement('script'); | |
| // Load it from the right place. | |
| var replacement = 'webcomponents-' + polyfills.join('-') + '.js'; | |
| var url = script.src.replace(name, replacement); | |
| newScript.src = url; | |
| // NOTE: this is required to ensure the polyfills are loaded before | |
| // *native* html imports load on older Chrome versions. This *is* CSP | |
| // compliant since CSP rules must have allowed this script to run. | |
| // In all other cases, this can be async. | |
| if (document.readyState === 'loading' && ('import' in document.createElement('link'))) { | |
| document.write(newScript.outerHTML); | |
| } else { | |
| document.head.appendChild(newScript); | |
| } | |
| } else { | |
| // Ensure `WebComponentsReady` is fired also when there are no polyfills loaded. | |
| // however, we have to wait for the document to be in 'interactive' state, | |
| // otherwise a rAF may fire before scripts in <body> | |
| var fire = function() { | |
| requestAnimationFrame(function() { | |
| window.WebComponents.ready = true; | |
| document.dispatchEvent(new CustomEvent('WebComponentsReady', {bubbles: true})); | |
| }); | |
| }; | |
| if (document.readyState !== 'loading') { | |
| fire(); | |
| } else { | |
| document.addEventListener('readystatechange', function wait() { | |
| fire(); | |
| document.removeEventListener('readystatechange', wait); | |
| }); | |
| } | |
| } | |
| })(); |