node js pipe stream

gistfile1.txt

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

http.createServer(function(req, res) {
    res.writeHead(200, {'Content-Type': 'image/png'});
    fs.createReadStream('./haha.png').pipe(res);
    
}).listen(3000);
console.log('server running at localhost:3000');