面试题-lazyMan实现

原文:如何实现一个LazyMan

面试题目

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(5).eat('dinner'),输出:

Hi, This is Hank!
// 等待5秒
Weak 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'),输出

// 等待5秒
Wake up after 5
Hi, this is Hank!
Eat supper

以此类推

题目解析

  • 需要封装一个对象,并且这个对象提供不同的方法,比如eat
  • 能进行链式调用,那么每个调用方法,都必须返回当前对象
  • sleepsleepFirst方法需要时异步的

解题思路

  • 采用 ES6 的 class,来实现,封装对象_LazyMan
  • 提供一系列方法,比如eatsleepsleepFirst异步方法采用PromisesetTimeout实现
  • 链式调用,考虑到其中含异步方法,采用任务队列及 ES6 的async wait实现。每次调用都往队列中加入方法,然后循环调用任务队列,而循环中通过异步实现异步的方法,保证正确。

具体实现

class _LazyMan {
  constructor (name) {
    this.taskQueue = [];
    this.runTimer = null;
    this.sayHi(name);
  }

  run () {
    if (this.runTimer) {
      clearTimeout(this.runTimer);
    }

    this.runTimer = setTimeout(async () => {
      for (let asyncFun of this.taskQueue) {
        await asyncFun()
      }
      this.taskQueue.length = 0;
      this.runTimer = null;
    })
    return this;
  }

  sayHi (name) {
    this.taskQueue.push(async () => console.log(`Hi, this is ${name}`));
    return this.run();
  }

  eat (food) {
    this.taskQueue.push(async () => console.log(`Eat ${food}`));
    return this.run();
  }

  sleep (second) {
    this.taskQueue.push(async () => {
      console.log(`Sleep ${second} s`)
      return this._timeout(second)
    });
    return this.run();
  }

  sleepFirst (second) {
    this.taskQueue.unshift(async () => {
      console.log(`Sleep first ${second} s`)
      return this._timeout(second);
    });
    return this.run();
  }

  async _timeout (second) {
    await new Promise(resolve => {
      setTimeout(resolve, second * 1e3);
    })
  }
}

// 测试
var LazyMan = name => new _LazyMan(name)

// lazyMan('Hank');
lazyMan('Hank').sleep(10).eat('dinner');
// lazyMan('Hank').eat('dinner').eat('supper');
// lazyMan('Hank').sleepFirst(5).eat('supper');
posted @ 2018-10-28 16:52  ESnail  阅读(2489)  评论(0编辑  收藏  举报