# How to shuffle elements in a JavaScript array

> Learn how to shuffle the elements of a JavaScript array by calling sort() with a function that returns Math.random() minus 0.5 for a random order each time.

Author: [Flavio Copes](https://flaviocopes.com/about/) | Published: 2020-05-30 | Topics: [JavaScript](https://flaviocopes.com/tags/js/) | Canonical: https://flaviocopes.com/how-to-shuffle-array-javascript/

Short answer: 

```js
let list = [1, 2, 3, 4, 5, 6, 7, 8, 9]
list = list.sort(() => Math.random() - 0.5)
```

Long answer:

I had the need to shuffle the elements in a [JavaScript](https://flaviocopes.com/javascript/) array. 

In other words, I wanted to remix the array elements, to have them in a different order than the previous one.

Starting from an array like this:

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

I wanted something different any time I ran the operation, like this:

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

Here is the process I came up with. Given the array `list`:

```js
const list = [1, 2, 3, 4, 5, 6, 7, 8, 9]
```

We can call the `sort()` method, which accepts a function that returns a value between -0.5 and 0.5:

```js
list.sort(() => Math.random() - 0.5)
```

This function is ran for every element in the array. You can pass 2 elements of the array, like this: `list.sort((a, b) => Math.random() - 0.5)` but in this case we're not using them. If the result of this operation is < 0, the element `a` is put to an index lower than `b`, and the opposite if the result is > 0.

You can [read all the details on Array.sort() here](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort).

Calling `sort()` on a list does not change the original array value.

Now you can assign the result of this operation to a new variable, like this:

```js
const shuffled = list.sort(() => Math.random() - 0.5)
```

or you can also overwrite the existing list, if you declare that as a `let` variable:

```js
let list = [1, 2, 3, 4, 5, 6, 7, 8, 9]
list = list.sort(() => Math.random() - 0.5)
```