1  /**
 2   * Copies the values of `source` to `array`.
 3   *
 4   * @private
 5   * @param {Array} source The array to copy values from.
 6   * @param {Array} [array=[]] The array to copy values to.
 7   * @returns {Array} Returns `array`.
 8   */
 9  function copyArray(source, array) {
10    var index = -1,
11        length = source.length;
12  
13    array || (array = Array(length));
14    while (++index < length) {
15      array[index] = source[index];
16    }
17    return array;
18  }
19  
20  module.exports = copyArray;