How to randomize (shuffle) a JavaScript array?

I have an array like this:

var arr1 = ["a", "b", "c", "d"];

How can I randomize / shuffle it?


The de-facto unbiased shuffle algorithm is the Fisher-Yates (aka Knuth) Shuffle.


You can see a great visualization here (and the original post linked to this)

function shuffle(array) {
  var currentIndex = array.length, temporaryValue, randomIndex;

  // While there remain elements to shuffle...
  while (0 !== currentIndex) {

    // Pick a remaining element...
    randomIndex = Math.floor(Math.random() * currentIndex);
    currentIndex -= 1;

    // And swap it with the current element.
    temporaryValue = array[currentIndex];
    array[currentIndex] = array[randomIndex];
    array[randomIndex] = temporaryValue;

  return array;

// Used like so
var arr = [2, 11, 37, 42];

Some more info about the algorithm used.