Promise 簡潔應用模板

function pTest () {
  let pro = new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve('誰知道是個什麼玩意呢')
    }, 1000)
  })
  return pro
}

function pTry () {
  let prom = new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve('隨便猜猜是個什麼玩意唄')
    }, 5000)
  })
  return prom
}

pTest().then(res => {
  console.log('1')
  console.log(res)
  return pTry()
}).then(res => {
  console.log('2')
  console.log(res)
  return pTest()
}).then(res => {
  console.log('3')
  console.log(res)
  return pTry()
}).then(res => {
  console.log('4')
  console.log(res)
})