How can I send some text from browser javascript to node.js code (not in the browser)?

Question

I think it's not the hardest problem, but i can't solve it. I have some html, css and javascript code. On a html-page the user can enter a number into a searchfield. The goal is to have this number in my node.js code to do more stuff with it.

My ideas so far:

• create a cookie: worked fine until i had to get this somehow to my node.js code
• browserify: can't work because of security reasons

than i tried the following:

on the server side:

var http = require('http');
http.createServer(function (req, res) {

    console.log('Request received');

    res.writeHead(200, { 
        'Content-Type': 'text/plain',
        'Access-Control-Allow-Origin': '*' // implementation of CORS
    });
    req.on('data', function (chunk) {
        console.log('GOT DATA!');
    });

    res.end('{"msg": "OK"}'); 

}).listen(8080, '172.0.0.1');
console.log('Server running at http://172.0.0.1:8080/');

and on the client side i tried first this:

var request = new XMLHttpRequest();
request.open('POST', cookie); // cookie is the text that i would like to transfer
request.setRequestHeader('Content-Type', 'text/*;charset=utf-8');
request.send(cookie);

and then this:

$.ajax({
    type: 'POST',
    url: 'http://172.0.0.1',
    data: '{"data": cookie}', // cookie = my text
    crossDomain: true,
    success: function (data) {
        var ret = jQuery.parseJSON(data);
        console.log(ret.msg);
    },
    error: function (xhr, status, error) {
        console.log('Error: ' + error.message);
        console.log('Error connecting to the server.');
    }
});

The problem is No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost' is therefore not allowed access.

If i'm calling the server in the browser i get {"msg": "OK"}. That is nice, but how can i get to my cookie text in the node.js code.

I'm new to this node.js, ajax - world. Maybe there is just a little piece missing.