非同步機制

const userTable = { '1': { money: 10000 } }

function withdraw (id, money) {
  userTable[id].money -= money
}

function deposit (id, money) {
  const currentMoney = userTable[id].money
  currentMoney += money
  userTable[id].money = currentMoney
}

withdraw('1', 10000) // 0

deposit('1', 1000) // 1000

const money1 = userTable[id].money
const money2 = userTable[id].money // *
money1 -= 10000
userTable[id].money = money1

money2 += 1000 // 認為餘額還是 10000
userTable[id].money = money2

// 11000, 現賺 10000 (也可能變 0)

function bar () { console.log('baz') }
function foo () { bar() }
setTimeout(() => { console.log('setTimeout') }, 1000)
setInterval(() => { console.log('setInterval') }, 5000)
foo()

setTimeout(() => {
  console.log('setTimeout')
})

new Promise(resolve => {
  console.log('promise executor')
  resolve()
})
  .then(() => {
    console.log('promise then')
  })

console.log('main')

async function async1() {
  new Promise(async resolve => {
    Promise.resolve()
      .then(() => {
        console.log(0)
        resolve()
      })
  })
    .then(() => {
      console.log(1)
    })
  await async2()
  console.log(2)
}
async function async2() {
  async3()
  console.log(3)
}
function async3() {
  new Promise((resolve) => resolve())
    .then(() => {
      console.log(4)
    })
  Promise.resolve()
    .then(() => {
      console.log(5)
    })
}

async1()

setTimeout(function() {
  console.log(6)
}, 0)

new Promise(resolve => {
  console.log(7)
  resolve()
})
  .then(function() {
    console.log(8)
  })
  .then(function() {
    console.log(9)
  })