JavaScript: Randomly arrange or shuffle an array

Last update on May 30 2022 10:07:49 (UTC/GMT +8 hours)

JavaScript Array: Exercise-17 with Solution

Write a JavaScript program to shuffle an array.

Sample Solution:

HTML Code:

<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>Shuffle an array</title>
</head>
<body>
</body>
</html>

JavaScript Code:

function shuffle(arra1) {
    var ctr = arra1.length, temp, index;

// While there are elements in the array
    while (ctr > 0) {
// Pick a random index
        index = Math.floor(Math.random() * ctr);
// Decrease ctr by 1
        ctr--;
// And swap the last element with it
        temp = arra1[ctr];
        arra1[ctr] = arra1[index];
        arra1[index] = temp;
    }
    return arra1;
}
var myArray = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
console.log(shuffle(myArray));

Sample Output:

[5,3,0,9,8,2,1,4,7,6]

Flowchart:

ES6 Version:

function shuffle(arra1) {
    let ctr = arra1.length;
    let temp;
    let index;

    // While there are elements in the array
    while (ctr > 0) {
// Pick a random index
        index = Math.floor(Math.random() * ctr);
// Decrease ctr by 1
        ctr--;
// And swap the last element with it
        temp = arra1[ctr];
        arra1[ctr] = arra1[index];
        arra1[index] = temp;
    }
    return arra1;
}
const myArray = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
console.log(shuffle(myArray));

Live Demo:

See the Pen JavaScript - Randomly arrange or shuffle an array - array-ex- 17 by w3resource (@w3resource) on CodePen.

Improve this sample solution and post your code through Disqus

Previous: Write a JavaScript program to find the leap years from a given range of years
Next: Write a JavaScript program to perform a binary search.

JavaScript: Tips of the Day

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = []; arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; arr[3] = "Kai Jim"; arr[4] = "Borge"; console.log(arr.join()); arr.splice(2, 0, "Lene"); console.log(arr.join());

Ref: https://bit.ly/2BXbp04