recursion v.s. iteration

fibonacci.js

const recursion = n => {
  if (n === 0) return 0;
  if (n === 1) return 1;

  return recursion(n - 1) + recursion(n - 2);
};

const iteration = n => {
  if (n === 0) return 0;
  if (n === 1) return 1;

  let prev = 0;
  let cur = 1;
  let newCur;
  for (let i = 2; i < n + 1; i++ ) {

    newCur = prev + cur;
    prev = cur;
    cur = newCur;
  }

  return cur;
};

const test = input => {
  let start;
  let time;

  start = Date.now();
  recursion(input);
  time = Date.now() - start;
  console.log(time);

  start = Date.now();
  iteration(input);
  time = Date.now() - start;
  console.log(time);
}

test(45);
// 13392
// 0

test(46);
// 21487
// 2

test(47);
// 34554
// 0