_shuffleSelf.js

define(['./_baseRandom'], function(baseRandom) {

  /** Used as a safe reference for `undefined` in pre-ES5 environments. */
  var undefined;

  /**
   * A specialized version of `_.shuffle` which mutates and sets the size of `array`.
   *
   * @private
   * @param {Array} array The array to shuffle.
   * @param {number} [size=array.length] The size of `array`.
   * @returns {Array} Returns `array`.
   */
  function shuffleSelf(array, size) {
    var index = -1,
        length = array.length,
        lastIndex = length - 1;

    size = size === undefined ? length : size;
    while (++index < size) {
      var rand = baseRandom(index, lastIndex),
          value = array[rand];

      array[rand] = array[index];
      array[index] = value;
    }
    array.length = size;
    return array;
  }

  return shuffleSelf;
});