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JavaScript - sort in random order

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Created by:

telsa

502

In this short article, we would like to show how to sort array items in random order in JavaScript.

Quick solution:

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array.sort(() => Math.random() - 0.5);

Warning: Array sort() method changes input array items order.

Reusable function

Edit

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const sortRandomly = (array) => array.sort(() => Math.random() - 0.5);
​
​
// Usage example:
​
const array = [1, 2, 3, 4, 5];
​
console.log(array);   // [1, 2, 3, 4, 5]
sortRandomly(array);  // <----- random sort function call
console.log(array);   // [3, 4, 5, 2, 1]

Auto running

Fisher–Yates shuffle algorithm

Edit

The below example implements Fisher–Yates shuffle algorithm:

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const randomInteger = (max) => {
    return Math.floor(max * Math.random());
};
​
const sortRandomly = (array) => {
    for (let i = array.length - 1; i > 0; --i) {
        const j = randomInteger(i + 1);
        const tmp = array[i];
        array[i] = array[j];
        array[j] = tmp;
    }
};
​
​
// Usage example:
​
const array = [1, 2, 3, 4, 5];
​
console.log(array);   // [1, 2, 3, 4, 5]
sortRandomly(array);  // <----- random sort function call
console.log(array);   // [3, 4, 5, 2, 1]