原生js如何实现观察者和订阅者模式

// eventProxy.js
'use strict';
const eventProxy = {
 onObj: {},
 oneObj: {},
 on: function(key, fn) {
  if(this.onObj[key] === undefined) {
   this.onObj[key] = [];
  }
 
  this.onObj[key].push(fn);
 },
 one: function(key, fn) {
  if(this.oneObj[key] === undefined) {
   this.oneObj[key] = [];
  }
 
  this.oneObj[key].push(fn);
 },
 off: function(key) {
  this.onObj[key] = [];
  this.oneObj[key] = [];
 },
 trigger: function() {
  let key, args;
  if(arguments.length == 0) {
   return false;
  }
  key = arguments[0];
  args = [].concat(Array.prototype.slice.call(arguments, 1));
 
  if(this.onObj[key] !== undefined
   && this.onObj[key].length > 0) {
   for(let i in this.onObj[key]) {
    this.onObj[key][i].apply(null, args);
   }
  }
  if(this.oneObj[key] !== undefined
   && this.oneObj[key].length > 0) {
   for(let i in this.oneObj[key]) {
    this.oneObj[key][i].apply(null, args);
    this.oneObj[key][i] = undefined;
   }
   this.oneObj[key] = [];
  }
 }
};
 
export default eventProxy;

import { eventProxy } from '@/utils'
 
class Parent extends Component{
 render() {
  return (
   <div style={{marginTop:"50px"}}>
    <Child_1/>
    <Child_2/>
   </div>
  );
 }
}
// componentDidUpdate 与 render 方法与上例一致
class Child_1 extends Component{
 componentDidMount() {
  setTimeout(() => {
   // 发布 msg 事件
   console.log(eventProxy)
   eventProxy.trigger('msg', 'end','lll');
  }, 5000);
 }
 render() {
  return (
   <div>我是组件一</div>
  )
 }
}
// componentDidUpdate 方法与上例一致
class Child_2 extends Component{
 state = {
  msg: 'start'
 };
 
 componentDidMount() {
  // 监听 msg 事件
  eventProxy.on('msg', (msg,mm) => {
   console.log(msg,mm)
   this.setState({
    msg:msg
   });
  });
 }
 
 render() {
  return <div>
   <p>child_2 component: {this.state.msg}</p>
  </div>
 }
}