express next function

nodejs 里面的next()这个函数调用的作用是什么呢?

var express = require('express');
var app = express();
var myLogger = function(req, res, next){
  console.log("Logger--");
  next();
}
app.use(myLogger);

app.get('/', function(req, res, next){
//  console.log(req);
  console.log('/');
  var buffer = new Buffer(6);
  buffer.fill('春天');
  console.log(buffer.toString());
  next();

  res.send({msg: 'hello,world!'});
}, function(req, res, next){
  console.log('next');
  next();
}, function(){
  console.log('next 2');
})

app.get('/user', function(req, res){
  console.log('/user');
  res.send('/user');
});
var server = app.listen(8081, '0.0.0.0', function(){
  var host = server.address().address;
  var port = server.address().port;
  console.log('http://%s:%s', host, port);
});

　　

参考： https://stackoverflow.com/questions/5384526/javascript-node-js-next