@webcomponents/custom-elements
Version:
HTML Custom Elements Polyfill
46 lines • 2.15 kB
JavaScript
;
/**
* @license
* Copyright (c) 2016 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
*/
/**
* This shim allows elements written in, or compiled to, ES5 to work on native
* implementations of Custom Elements v1. It sets new.target to the value of
* this.constructor so that the native HTMLElement constructor can access the
* current under-construction element's definition.
*/
(function () {
if (
// No Reflect, no classes, no need for shim because native custom elements
// require ES2015 classes or Reflect.
window.Reflect === undefined ||
window.customElements === undefined ||
// The webcomponentsjs custom elements polyfill doesn't require
// ES2015-compatible construction (`super()` or `Reflect.construct`).
window.customElements.polyfillWrapFlushCallback) {
return;
}
const BuiltInHTMLElement = HTMLElement;
/**
* With jscompiler's RECOMMENDED_FLAGS the function name will be optimized away.
* However, if we declare the function as a property on an object literal, and
* use quotes for the property name, then closure will leave that much intact,
* which is enough for the JS VM to correctly set Function.prototype.name.
*/
const wrapperForTheName = {
'HTMLElement': function HTMLElement() {
return Reflect.construct(BuiltInHTMLElement, [], this.constructor);
},
};
window.HTMLElement = wrapperForTheName['HTMLElement'];
HTMLElement.prototype = BuiltInHTMLElement.prototype;
HTMLElement.prototype.constructor = HTMLElement;
Object.setPrototypeOf(HTMLElement, BuiltInHTMLElement);
})();
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