# Array intersection based on function

JavaScript, Array · Oct 20, 2020

Returns the elements that exist in both arrays, using a provided comparator function.

- Use
`Array.prototype.filter()`

and`Array.prototype.findIndex()`

in combination with the provided comparator to determine intersecting values.

const intersectionWith = (a, b, comp) => a.filter(x => b.findIndex(y => comp(x, y)) !== -1); intersectionWith( [1, 1.2, 1.5, 3, 0], [1.9, 3, 0, 3.9], (a, b) => Math.round(a) === Math.round(b) ); // [1.5, 3, 0]