events模块

 /**
  * Created by Administrator on 2016/8/3.
  */
 var http = require("http");
 //Node 导入文件系统模块
 var fs = require("fs");
 //引入events模块
 var events = require("events");
 //创建eventEmitter对象
 var eventEmitter = new events.EventEmitter(); //注意大小写
 //绑定事件以及事件的处理程序
 eventEmitter.on("oneEvent",function(){
     //异步读取文件内容的函数: readFile()
     fs.readFile("index.txt", "utf-8", function(err, data){
         if(err){
             console.log(err);
         }else{
             console.log(data);
         }
     });
     console.log("end异步");
 });
 //触发事件
 eventEmitter.emit("oneEvent");
 function start(req, res){
     res.writeHead(200, {"Content-Type": "text/plain"});
     res.write("异步读取文件和同步读取文件的对比！");
     res.end("over");
 }
 //创建一个http服务器，并监听端口号为3001，host为127.1.1.1
 var server = http.createServer(start).listen("3002","127.1.1.1",function(){
     var port = server.address().port;
     var host = server.address().address;
     console.log("应用实例，访问地址为 http://%s:%s", host, port);
 });

//引入events模块
var events = require("events");

//创建eventEmitter对象
var eventEmitter = new events.EventEmitter(); //注意大小写

//绑定事件以及事件的处理程序
eventEmitter.on("eventName",function(){
    console.log("事件处理代码。");
});
//触发事件
eventEmitter.emit("eventName");