document.body.addEventListener('click', function(){ 
  alert(1);
}, false );

// 增加订阅者前者也不受影响
document.body.addEventListener('click', function(){ 
  alert(2);
}, false );

document.body.click(); // 模拟用户点击

const subscription = {};

// 订阅者列表
subscription.subscriber = [];

// 订阅函数
subscription.subscribe = function (fn) {
  this.subscriber.push(fn);
};

// 发布函数
subscription.publish = function () {
  this.subscriber.forEach((fn) => {
    fn.apply(this, arguments);
  });
};

// 粉丝 1 订阅
subscription.subscribe((article) => {
  console.log(`fans1 receive ${article}`);
});

// 粉丝 2 订阅
subscription.subscribe((article) => {
  console.log(`fans2 receive ${article}`);
});

// 订阅号发布
const article = 'article'
subscription.publish(article);
// fans1 receive article
// fans2 receive article

// 通用发布订阅模式
class EventEmitter {
  // 订阅者列表
  subscriber = {};

  // 订阅
  subscribe(key, fn) {
    if (!Array.isArray(this.subscriber[key])) {
      this.subscriber[key] = [];
    }
    this.subscriber[key].push(fn);
  }

  // 取消单个订阅
  unsubscribe(key, fn) {
    const subscribers = this.subscriber[key] || [];
    this.subscriber[key] = subscribers.filter((_fn) => _fn !== fn);
  }

  // 取消所有订阅
  unsubscribeAll(key) {
    this.subscriber[key] = [];
  }

  // 发布
  publish(key, ...args) {
    const subscribers = this.subscriber[key] || [];

    if (subscribers.length === 0) {
      console.log("has't subscriber");
    }

    subscribers.forEach((subscriber) => {
      subscriber.apply(this, args);
    });
  }
}

// 创建发布订阅信道中介
const e = new EventEmitter();

// 发布者
const publisher = {
  article1: 'article1',
  article2: 'article2',
};

// 订阅者
const subscriber1 = (article) => {
  console.log(`fans1 receive ${article}`);
};
const subscriber2 = (article) => {
  console.log(`fans2 receive ${article}`);
};

// 订阅操作
e.subscribe('event1', subscriber1);
e.subscribe('event1', subscriber2);

// 发布操作
e.publish('event1', publisher.article1);
// fans1 receive article1
// fans2 receive article1

// 多事件发布订阅
e.subscribe('event2', subscriber1);
e.publish('event2', publisher.article1);
// fans1 receive article1

// 取消单个订阅
e.unsubscribe('event1', subscriber1);
e.publish('event1', publisher.article2);
// fans2 receive article2

// 取消所有订阅
e.unsubscribeAll('event1');
e.publish('event1');
// has't subscriber

// 控制台页面
function openApp(){
    userStore.getPermission();
    appStore.getAppInfo();
    settingStore.getAppSetting();
    dataStore.resetDataCache();
}

// event.js
// 创建全局发布订阅信道
export const event = new EventEmitter();
// 集中维护事件名称  避免命名冲突
export const EVENT_TYPE = {
  OPEN_APP: 'OPEN_APP',
};

// user.js
event.subscribe(EVENT_TYPE.OPEN_APP, getPermission);
// app.js
event.subscribe(EVENT_TYPE.OPEN_APP, getAppInfo);
// setting.js
event.subscribe(EVENT_TYPE.OPEN_APP, getAppSetting);
// data.js
event.subscribe(EVENT_TYPE.OPEN_APP, resetDataCache);

// console.js
function openApp(){
  event.publish(EVENT_TYPE.OPEN_APP);
}