countDown-withTrampoline.js

// the trampoline wrapper function
const trampoline = fn => (...args) => {
  let result = fn(...args)
  while (typeof result === 'function') {
    result = result()
  }
  return result
}

const countDown = (n) => {
  console.log(n);
  // calling countdown with () => {}
  return (n > 0) ? () => countDown(n - 1) : n;
}

const num = 99999;
// wrapping countDown with the trampoline
const withTrampoline = trampoline(countDown(num));
withTrampoline(num);