# Array symmetric difference

JavaScript, Array, Math · Oct 22, 2020

Returns the symmetric difference between two arrays, without filtering out duplicate values.

- Create a
`Set`

from each array to get the unique values of each one. - Use
`Array.prototype.filter()`

on each of them to only keep values not contained in the other.

```
const symmetricDifference = (a, b) => {
const sA = new Set(a),
sB = new Set(b);
return [...a.filter(x => !sB.has(x)), ...b.filter(x => !sA.has(x))];
};
```

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