angular-docs-cn/packages/core/src/util/array_utils.ts

/**
 * @license
 * Copyright Google Inc. All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

/**
* Equivalent to ES6 spread, add each item to an array.
*
* @param items The items to add
* @param arr The array to which you want to add the items
*/
export function addAllToArray(items: any[], arr: any[]) {
  for (let i = 0; i < items.length; i++) {
    arr.push(items[i]);
  }
}

/**
 * Flattens an array in non-recursive way. Input arrays are not modified.
 */
export function flatten(list: any[], mapFn?: (value: any) => any): any[] {
  const result: any[] = [];
  let i = 0;
  while (i < list.length) {
    const item = list[i];
    if (Array.isArray(item)) {
      if (item.length > 0) {
        list = item.concat(list.slice(i + 1));
        i = 0;
      } else {
        i++;
      }
    } else {
      result.push(mapFn ? mapFn(item) : item);
      i++;
    }
  }
  return result;
}