10. 实现一个GreetRobot，使之具有以下能力

[senfish]

// 实现一个GreetRobot，使之具有以下能力
// 1. 执行GreetRobot('bb8')
//    输出: Hi this is bb8!
   
// 2. 执行GreetRobot('bb8').greet('Bob')
//    输出: Hi this is bb8! 
//         Nice to meet you Bob.
        
// 3. 执行GreetRobot('bb8').greet('Bob').greet('Jerry')
//    输出: Hi this is bb8! 
//         Nice to meet you Bob.
//         Nice to meet you Jerry.
        
// 4. 执行GreetRobot('bb8').greet('Bob').greetVip('Mike')
//    输出: Glad to see you Mike~
//         Hi this is bb8!  
//         Nice to meet you Bob.
        
// 5. 执行GreetRobot('bb8').greetVip('Marry').greetVip('Mike')
//    输出: Glad to see you Mike~
//         Glad to see you Marry~
//         Hi this is bb8!

[senfish]

维护一个数组函数的队列，每个函数负责打印内容；
当所有的函数触发之后，再去执行数组函数

• es5利用原型

function GreetRobot(name) {
  GreetRobot.prototype.listeners = [() => console.log(`Hi this is ${name}!`)]
  setTimeout(() => {
    GreetRobot.prototype.listeners.forEach(l => l())
  })
  return GreetRobot.prototype;
}
GreetRobot.prototype.listeners = [];

GreetRobot.prototype.greet = function (name) {
  this.listeners.push(() => console.log(`Nice to meet you ${name}`));
  return this;
}

GreetRobot.prototype.greetVip = function (name) {
  this.listeners.unshift(() => console.log(`Glad to see you ${name}~`));
  return this;
}

• es6利用类

function GreetRobot(name) {
  return new class {
    constructor() {
      this.listeners = [() => console.log(`Hi this is ${name}!`)];
      this.run();
    }
    run() {
      setTimeout(() => {
        this.listeners.forEach(l => l());
      }, 200)
    }
    greet(name) {
      this.listeners.push(() => console.log(`Nice to meet you ${name}`))
      return this;
    }
    greetVip(name) {
      this.listeners.unshift(() => console.log(`Glad to see you ${name}~`))
      return this;
    }
  }
}