com.google.javascript.jscomp.js.es6.array.copywithin.js Maven / Gradle / Ivy

Go to download
/*
 * Copyright 2016 The Closure Compiler Authors.
 *
 * 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.
 */

'require util/polyfill';

$jscomp.polyfill('Array.prototype.copyWithin', function(orig) {
  if (orig) return orig;

  /**
   * Copies elements from one part of the array to another.
   *
   * @this {!IArrayLike}
   * @param {number} target Start index to copy elements to.
   * @param {number} start Start index to copy elements from.
   * @param {number=} opt_end Index from which to end copying.
   * @return {!IArrayLike} The array, with the copy performed in-place.
   * @template VALUE
   */
  var polyfill = function(target, start, opt_end) {
    var len = this.length;
    target = Number(target);
    start = Number(start);
    opt_end = Number(opt_end != null ? opt_end : len);
    if (target < start) {
      opt_end = Math.min(opt_end, len);
      while (start < opt_end) {
        if (start in this) {
          this[target++] = this[start++];
        } else {
          delete this[target++];
          start++;
        }
      }
    } else {
      opt_end = Math.min(opt_end, len + start - target);
      target += opt_end - start;
      while (opt_end > start) {
        if (--opt_end in this) {
          this[--target] = this[opt_end];
        } else {
          delete this[target];
        }
      }
    }
    return this;
  };

  return polyfill;
}, 'es6-impl', 'es3');