start to use Javascript to make a recursion algorithms

recursion.js

function factorial (num) {
  if (num === 1) {
    return num
  } else {
    return num * factorial(num - 1)
  }
}
factorail(5)      

#LIFO 觀念

function last () {
  console.log('後來才進堆疊')
}

function first () {
  console.log('先進堆疊 - start')
  last()
  console.log('先進堆疊 - end')
}

first()    // "先進堆疊 - start" -> "後來進堆疊" -> "先進堆疊 - end"