node js - check button submitted by method

// By: facebook.com/muhammad.sukron.52

var http = require('http');

//to read file
var fs = require('fs');

var server = http.createServer(function(req, res) {
    if(req.url == '/') {
        switch(req.method) {
            case 'GET':
                set_form(res);
                break;

            case 'POST':
                res.end('Button Submitted');
                break;
        }
    }
});

function set_form(res) {
    fs.readFile('form.html', function(err, data) {
        res.write(data);
        res.end();
    });
}

server.listen(3400);
console.log('server is running');