polygerrit-ui/app/scripts/hiddenscroll.js

/**
 * @license
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

(function(window) {
  window.Gerrit = window.Gerrit || {};
  if (window.Gerrit.hasOwnProperty('hiddenscroll')) { return; }

  window.Gerrit.hiddenscroll = undefined;

  window.addEventListener('WebComponentsReady', () => {
    const elem = document.createElement('div');
    elem.setAttribute(
        'style', 'width:100px;height:100px;overflow:scroll');
    document.body.appendChild(elem);
    window.Gerrit.hiddenscroll = elem.offsetWidth === elem.clientWidth;
    elem.remove();
  });
})(window);