Fib function as showed on https://twitter.com/HarmanManchanda/status/1198347925039939584

fib-function.js

const memoize = (fn) => {
  const cache = {};
  return (...args) => {
    if (cache[args]) { return cache[args]; }
    cache[args] = fn.apply(this, args);
    return cache[args];
  };
};

const range = (count) => Array.from({ length: count }, (v, i) => i + 1);

let fibGen = (n) => (n < 2) ? n : fibGen(n - 1) + fibGen(n - 2);
fibGen = memoize(fibGen);

const fib = (items) => {
  let all = [0];
  if (items > 0) for (i of range(items)) all.push(fibGen(i));
  return all;
};