观察者模式 / 发布订阅

[ZhangHanwen96]

订阅发布模式

// 订阅发布模式
var events = (function(){
    var topics = {};

    return {
        subscribe: function(topic, handler) {
            if(!topics.hasOwnProperty(topic)) {
                topics[topic] = [];
            }
            topics[topic].push(handler);
        },

        public: function(topic, info) {
            if(topics.hasOwnProperty(topic)) {
                topics[topic].forEach(handler => handler(info));
            }
        },

         unsubscribe: function(topic, handler) {
            if(!topics.hasOwnProperty(topic)) return;

            topics[topic] = topics[topic].filter(item => item !== handler);
        },

        removeAll: function(topic) {
            if(topics.hasOwnProperty(topic)) {
                topics[topic] = [];
            }
        }
    }
})()

观察者

class Observer {
    constructor(name) {
        this.name = name
    }

    update(value) {
        console.log(`${this.name} has recived message from subject + ${value}`)
    }
}

class ObserverList {
    constructor() {
        this.observerList = []
    }

    add(ob) {
        return this.observerList.push(ob);
    }

    remove(ob) {
        this.observerList.filter(observer => ob != observer);
    }

    getList() {
        return this.observerList;
    }
}

class Subject {
    constructor() {
        this.observers = new ObserverList();
    }

    addObserver(ob) {
        this.observers.add(ob);
    }

    removeObserver(ob) {
        this.observers.remove(ob);
    }

    notify(...args) {
        for(let ob of this.observers.getList()) {
            ob.update(...args)
        } 
    }
}