我们在日常开发使用经常遇到一些场景需要使用到观察者模式，比如登录成功需要改动同步页面多个模块的信息，这时最佳选择是使用observer 观察者模式。

class Apm {
    constructor(){
        //观察者模式
        this.observer = {
            //订阅
            addSubscriber: function (callback, opt) {
                this.subscribers[this.subscribers.length] = {
                    callback: callback,
                    opt: (opt !== 'undefined') ? opt : {}
                };
            },
            //退订
            removeSubscriber: function (callback) {
                for (var i = 0; i < this.subscribers.length; i++) {
                    if (this.subscribers[i].callback === callback) {
                        delete (this.subscribers[i]);
                    }
                }
            },
            //发布
            publish: function (what, _observer) {
                for (var i = 0; i < this.subscribers.length; i++) {
                    if (typeof this.subscribers[i].callback === 'function') {
                        
                        let observer = (_observer !== 'undefined') ? _observer : {};
                        // 执行注册的各种回调
                        this.subscribers[i].callback({ret: what, opt: this.subscribers[i].opt, observer: observer});
                    }
                }
            },
            // 将对象o具有观察者功能
            make: function (o) { 
                for (var i in this) {
                    o[i] = this[i];
                    o.subscribers = [];
                }
            }
        };
        this.observerLogin = {
            success: function (ret) {
                this.publish(ret, {type: 'success'});
            },
            error: function(ret){
                this.publish(ret, {type: 'error'});
            }
        };
        this.observer.make(this.observerLogin);
    }
}

链接: https://fly63.com/article/detial/2741