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

intersection

Returns a list of elements that exist in both 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]