30-seconds-of-code/snippets/array-intersection.md

Array intersection (Common values between two arrays)

Create a Set from b, then use Array.filter() on a to only keep values contained in b.

const intersection = (a, b) => { const s = new Set(b); return a.filter(x => s.has(x)); }
// intersection([1,2,3], [4,3,2]) -> [2,3]