Why do i not use request.end() but it still works?

i am new on node,and i just try the basic request&response function,the server side code is:

var http = require('http');
var querystring = require('querystring');

var server = http.createServer().listen(8124);

server.on('request', function(request, response) {

    if (request.method == 'POST') {
        var body = '';

        request.on('data', function(data) {
            body += data;

        });

        request.on('end', function() {
            var post = querystring.parse(body);
            console.log(post);
            response.writeHead(200, { 'Content-Type': 'text/plain' });
            response.end('Hello World!!!\n');
        });
    }

});

console.log('Server listening on 8214 ');

And the client side code is:

var http = require('http');
var querystring = require('querystring');

var postData = querystring.stringify({
    'msg': 'Hello World!'
});

var options = {
    hostname: 'localhost',
    port: 8124,
    method: 'POST',
    headers: {
        'Content-Type': 'application/x-www-form-urlencoded',
        'Content-Length': postData.length
    }
};

var request = http.request(options, function(response) {
    console.log('STATUS:' + response.statusCode);
    console.log('HEADERS' + JSON.stringify(response.headers));
    response.setEncoding('utf8');

    response.on('data', function(chuck) {
        console.log('BODY:' + chuck);
    });

    response.on('end', function() {
        console.log('No more data in response!');
    })
});

request.on('error', function(e) {
    console.log('problem with request: ' + e.message);
});

request.write(postData);
//request.end();

I comment out request.end()，but request.on('end', function() {...}); still works,I don't know why,please tell me what happened,thank you very much!!

via James Wei