# Cartesian product

JavaScript, Math · Dec 29, 2020

Calculates the cartesian product of two arrays.

- Use
`Array.prototype.reduce()`

,`Array.prototype.map()`

and the spread operator (`...`

) to generate all possible element pairs from the two arrays.

```
const cartesianProduct = (a, b) =>
a.reduce((p, x) => [...p, ...b.map(y => [x, y])], []);
```

```
cartesianProduct(['x', 'y'], [1, 2]);
// [['x', 1], ['x', 2], ['y', 1], ['y', 2]]
```