# N random elements in array

JavaScript, Array, Random · Oct 22, 2020

Gets `n`

random elements at unique keys from an array up to the size of the array.

- Shuffle the array using the Fisher-Yates algorithm.
- Use
`Array.prototype.slice()`

to get the first`n`

elements. - Omit the second argument,
`n`

, to get only one element at random from the array.

```
const sampleSize = ([...arr], n = 1) => {
let m = arr.length;
while (m) {
const i = Math.floor(Math.random() * m--);
[arr[m], arr[i]] = [arr[i], arr[m]];
}
return arr.slice(0, n);
};
```

```
sampleSize([1, 2, 3], 2); // [3, 1]
sampleSize([1, 2, 3], 4); // [2, 3, 1]
```