polygerrit-ui/app/behaviors/async-foreach-behavior/async-foreach-behavior.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.
 */

/** @polymerBehavior AsyncForeachBehavior */
export const AsyncForeachBehavior = {
  /**
   * @template T
   * @param {!Array<T>} array
   * @param {!Function} fn An iteratee function to be passed each element of
   *     the array in order. Must return a promise, and the following
   *     iteration will not begin until resolution of the promise returned by
   *     the previous iteration.
   *
   *     An optional second argument to fn is a callback that will halt the
   *     loop if called.
   * @return {!Promise<undefined>}
   */
  asyncForeach(array, fn) {
    if (!array.length) { return Promise.resolve(); }
    let stop = false;
    const stopCallback = () => { stop = true; };
    return fn(array[0], stopCallback).then(exit => {
      if (stop) { return Promise.resolve(); }
      return this.asyncForeach(array.slice(1), fn);
    });
  },
};

// TODO(dmfilippov) Remove the following lines with assignments
// Plugins can use the behavior because it was accessible with
// the global Gerrit... variable. To avoid breaking changes in plugins
// temporary assign global variables.
window.Gerrit = window.Gerrit || {};
window.Gerrit.AsyncForeachBehavior = AsyncForeachBehavior;