Arrays that look just like regular JavaScript arrays, but are computed lazily. Like Scala or Haskell's lazy streams (see https://stackoverflow.com/a/44333876/435124).
npm i lazy-arr -S
import { lazy } from 'lazy-arr'
let fibs = lazy([0, 1])(_ => fibs[_ - 1] + fibs[_ - 2])
fibs[0] // 0
fibs[1] // 1
fibs[10] // 55
MIT