const isHappy = function(n) {
  let set = new Set()
  let temp = calculate(n)
  if(set.has(temp)) return false

  if (temp === 1) return true

  set.add(temp)
  return isHappy(temp)
}

const calculate = n =>
  [...n.toString().replace(/^0+/, '')].reduce((acc, e) => {
    return acc + Math.pow(parseInt(e), 2)
  }, 0)

// that won't work with an error of Maximum call stack reached, cause I was letting new Set all the time.