webcomponentsjs/src/post-polyfill.js

/**
 * @license
 * Copyright (c) 2014 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';

  var customElements = window['customElements'];
  var HTMLImports = window['HTMLImports'];

  if (customElements && customElements['polyfillWrapFlushCallback']) {
    // Here we ensure that the public `HTMLImports.whenReady`
    // always comes *after* custom elements have upgraded.
    var flushCallback;
    var runAndClearCallback = function runAndClearCallback() {
      if (flushCallback) {
        var cb = flushCallback;
        flushCallback = null;
        cb();
        return true;
      }
    }
    var origWhenReady = HTMLImports['whenReady'];
    customElements['polyfillWrapFlushCallback'](function(cb) {
      flushCallback = cb;
      origWhenReady(runAndClearCallback);
    });

    HTMLImports['whenReady'] = function(cb) {
      origWhenReady(function() {
        // custom element code may add dynamic imports
        // to match processing of native custom elements before
        // domContentLoaded, we wait for these imports to resolve first.
        if (runAndClearCallback()) {
          HTMLImports['whenReady'](cb);
        } else {
          cb();
        }
      });
    }

  }

  HTMLImports['whenReady'](function() {
    requestAnimationFrame(function() {
      document.dispatchEvent(new CustomEvent('WebComponentsReady', {bubbles: true}));
    });
  });

})();