📘map, filter, reduce

Array methods replace most loops: filter keeps, map transforms, reduce aggregates.

They chain: scores.filter(s => s >= 10).map(s => s * 2) — reads like a sentence.

const doubled = [1, 2].map((n) => n * 2);
const sum = [1, 2, 3].reduce((acc, n) => acc + n, 0);