How to randomize (shuffle) a JavaScript array?
Posted By: Anonymous
I have an array like this:
var arr1 = ["a", "b", "c", "d"];
How can I randomize / shuffle it?
Solution
The de-facto unbiased shuffle algorithm is the Fisher-Yates (aka Knuth) Shuffle.
See https://github.com/coolaj86/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];
shuffle(arr);
console.log(arr);Some more info about the algorithm used.
Answered By: Anonymous
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