lodash/lodash.shuffle/index.js

/**
 * lodash 3.0.0 (Custom Build) <https://lodash.com/>
 * Build: `lodash modern modularize exports="npm" -o ./`
 * Copyright 2012-2015 The Dojo Foundation <http://dojofoundation.org/>
 * Based on Underscore.js 1.7.0 <http://underscorejs.org/LICENSE>
 * Copyright 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
 * Available under MIT license <https://lodash.com/license>
 */
var baseRandom = require('lodash._baserandom'),
    toIterable = require('lodash._toiterable');

/**
 * Creates an array of shuffled values, using a version of the
 * [Fisher-Yates shuffle](https://en.wikipedia.org/wiki/Fisher-Yates_shuffle).
 *
 * @static
 * @memberOf _
 * @category Collection
 * @param {Array|Object|string} collection The collection to shuffle.
 * @returns {Array} Returns the new shuffled array.
 * @example
 *
 * _.shuffle([1, 2, 3, 4]);
 * // => [4, 1, 3, 2]
 */
function shuffle(collection) {
  collection = toIterable(collection);

  var index = -1,
      length = collection.length,
      result = Array(length);

  while (++index < length) {
    var rand = baseRandom(0, index);
    if (index != rand) {
      result[index] = result[rand];
    }
    result[rand] = collection[index];
  }
  return result;
}

module.exports = shuffle;