node events set the event

1、let xx=require('events')

2、初始化事件对象
		let x=new xx.EventEmitter()
		
3、设置监听事件
	x.on('名称',回调函数);
	
4、触发监听事件
	x.emit('名称',传入回调参数);

Code Example:
asynchronous read disposed listener

let fs =require('fs');
let events=require('events')

//事件对象
let e=new events.EventEmitter();

//添加监听事件
e.on('ok',function(data){
	console.log(1);
})
e.on('ok',function(data){
	console.log(2);
})
e.on('ok',function(data){
	console.log(3);
})

//异步操作
function asRead(){
	return new Promise(function(resolve,reject){
		fs.readFile("C:/Users/10853/Desktop/tt.txt",{flag:'r',encoding:"utf-8"},function(err,data){
			resolve(data);
		})
	})
}

asRead().then((data)=>{
	e.emit('ok',data);
	console.log(data);
})

//第二种原始
fs.readFile("C:/Users/10853/Desktop/tt.txt",{flag:'r',encoding:"utf-8"},function(err,data){
	console.log(data);
	e.emit('ok',data);
})