Fisher-Yates Shuffle Algorithm

fisher-yates.js

/**
 * Shuffles array in place. Fisher-Yates algo.
 * @param {Array} a items An array containing the items.
 */
const shuffle = function(arr) {
  // Start i from the last element and move left. Swap with a random element to the left of i
  for (let i = arr.length - 1; i > 0; i--) {
    // j is a random element to the left of i
    const j = Math.floor(Math.random() * (i + 1));
    // Swap elements at i and j
    const temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;
  }
  return arr;
};