实现一个LazyMan

实现一个 LazyMan，可以按照以下方式调用：
LazyMan("Hank")
输出：Hi! This is Hank!

LazyMan("Hank").sleep(10).eat("dinner")
输出：Hi! This is Hank!
等待10秒..
Wake up after 10
Eat dinner

LazyMan("Hank").eat("dinner").eat("supper")
输出：Hi This is Hank!
Eat dinner
Eat supper

LazyMan("Hank").sleepFirst(5).eat("supper")
等待5秒
Wake up after 5
Hi This is Hank!
Eat supper

方法一：维护一个队列，在每个任务的结束调用 next 方法执行下一个任务。

class LazyMan {
  constructor(name) {
    this.name = name
    this.sayName = this.sayName.bind(this)
    this.next = this.next.bind(this)
    this.queue = [this.sayName]
    setTimeout(this.next, 0)
  }

  next(){
    const currTask = this.queue.shift()
    currTask && currTask()
  }

  sayName() {
    console.log(`Hi! this is ${this.name}!`)
    this.next()
  }

  holdOn(time) {
    setTimeout(() => {
      console.log(`Wake up after ${time} second`)
      this.next()
    }, time * 1000)
  }

  sleep(time) {
    this.queue.push(this.holdOn(time))
    return this
  }

  eat(meal) {
    this.queue.push(() => {
      console.log(`eat ${meal}`)
      this.next()
    })
    return this
  }

  sleepFirst(time) {
    this.queue.unshift(this.holdOn(time))
    return this
  }
}

const lazyMan = new LazyMan('abc')
lazyMan.sleep(10).eat('first')

方法二：Promise + async

class _LazyMan {
  constructor(name) {
    this.name = name
    this.sayName = this.sayName.bind(this)
    this.queue = [this.sayName]
    setTimeout(async () => {
      for (let todo of this.queue) {
        await todo()
      }
    }, 0)
  }

  sayName() {
    return new Promise((resolve) => {
      console.log(`Hi! this is ${this.name}!`)
      resolve()
    })
  }

  holdOn(time) {
    return () => new Promise(resolve => {
      setTimeout(() => {
        console.log(`Wake up after ${time} second`)
        resolve()
      }, time * 1000)
    })
  }

  sleep(time) {
    this.queue.push(this.holdOn(time))
    return this
  }

  eat(meal) {
    this.queue.push(() => {
      console.log(`eat ${meal}`)
    })
    return this
  }

  sleepFirst(time) {
    this.queue.unshift(this.holdOn(time))
    return this
  }
}

function LazyMan(name) {
  
  return new _LazyMan(name)
}

LazyMan('LiMing').sleep(10).eat('food')

LazyMan 有几样写法，你知道么？