(() => {
  setTimeout(() => {
    console.log(1)
  }, 0)
  Promise.resolve().then(() => {
    console.log(2)
  })
  Promise.resolve().then(() => {
    console.log(4)
  })
  console.log(3)
})()

// 2
(() => {
  setTimeout(() => {
    console.log(1)
  }, 0)
  new Promise((resolve) => {
    console.log(2)
    resolve()
  }).then(() => {
    console.log(3)
  }).then(() => {
    console.log(4)
  })
  console.log(5)
})()

// 3
(() => {
  const first = () => (new Promise((resolve, reject) => {
    console.log(3)
    let p = new Promise((resolve, reject) => {
      console.log(7)
      setTimeout(() => {
        console.log(5)
        resolve(6)
      }, 0)
      resolve(1)
    })
    resolve(2)
    p.then((arg) => {
      console.log(arg)
    })
  }))

  first().then((arg) => {
    console.log(arg)
  })

  console.log(4)
})()

// 4
(() => {
  setTimeout(() => {
    console.log("0")
  }, 0)
  new Promise((resolve, reject) => {
    console.log("1")
    resolve()
  }).then(() => {
    console.log("2")
    new Promise((resolve, reject) => {
      console.log("3")
      resolve()
    }).then(() => {
      console.log("4")
    }).then(() => {
      console.log("5")
    })
  }).then(() => {
    console.log("6")
  })

  new Promise((resolve, reject) => {
    console.log("7")
    resolve()
  }).then(() => {
    console.log("8")
  })
})()

// 5
(() => {
  Promise
    .resolve(1)
    .then(2)
    .then(Promise.resolve(3))
    .then(console.log)
})()