SOURCE

class Mediator {
    /**
     * 一个示例操作
     *
     * @param colleague 发送消息的同事类
     * @param message 消息内容
     */
    operate(colleague, message){
        throw new Error("This method must be overwritten!");
    }
}


class ConcreteMediator extends Mediator {
    constructor() {
        super();
        // 持有的具体同事类
        this.firstColleague = new FirstColleague(this),
        this.secondColleague = new SecondColleague(this);
    }
    operate(colleague, message) {
        // 同事类之间的交互通过中介者进行。
        // 这里只演示了两个同事类。
        if(colleague == this.firstColleague){
            this.secondColleague.receive(message);
        } else if(colleague == this.secondColleague) {
            this.firstColleague.receive(message);
        }
    }
}


class AbstractColleague {
    constructor(mediator) {
        this._mediator = mediator;
    }
    send(message) {
        throw new Error("This method must be overwritten!");
    }
    receive(message, sender) {
        throw new Error("This method must be overwritten!");
    }
}


class FirstColleague extends AbstractColleague{
    constructor(mediator) {
        super(mediator);
    }
    // 向中介者发送消息。
    send(message){
        this.mediator.operate(this, message);
    }
    // 从中介者接收到的消息。
    receive(message){
        console.log("First Colleague 收到消息：" + message);
    }
}

class SecondColleague extends AbstractColleague {
    constructor(mediator) {
        super(mediator);
    }
    // 向中介者发送消息。
    send(message) {
        //this.mediator.operate(this, message);
    }
    // 从中介者接收到的消息。
    receive(message) {
        console.log("Second Colleague 收到消息：" + message);
    }
}

// 把同事类注册到中介者
let mediator = new ConcreteMediator();
let firstColleague = new FirstColleague(mediator);
let secondColleague = new SecondColleague(mediator);
// 同事类之间通过中介者交互
firstColleague.send("Hello World");
secondColleague.send("Word Count");