This is easy if your Javascript engine supports XMLHttpRequest (XHR), which is ubiquitous on the web. Google it or see this page for details. I've provided a code snippet below. Read it carefully, particularly the comments on async being true and closures in response handlers. Also, this code is super lightweight as far as Javascript goes and I would expect it would work fine on just about any contemporary hardware footprint.

var url = http://www.google.com/;

var method = POST;

var postData = Some data;



// You REALLY want shouldBeAsync = true.

// Otherwise, it'll block ALL execution waiting for server response.

var shouldBeAsync = true;



var request = new XMLHttpRequest();



// Before we send anything, we first have to say what we will do when the

// server responds. This seems backwards (say how we'll respond before we send

// the request? huh?), but that's how Javascript works.

// This function attached to the XMLHttpRequest onload property specifies how

// the HTTP response will be handled. 

request.onload = function () {



   // Because of javascript's fabulous closure concept, the XMLHttpRequest request

   // object declared above is available in this function even though this function

   // executes long after the request is sent and long after this function is

   // instantiated. This fact is CRUCIAL to the workings of XHR in ordinary

   // applications.



   // You can get all kinds of information about the HTTP response.

   var status = request.status; // HTTP response status, e.g., 200 for 200 OK

   var data = request.responseText; // Returned data, e.g., an HTML document.

}



request.open(method, url, shouldBeAsync);



request.setRequestHeader(Content-Type, application/json;charset=UTF-8);

// Or... request.setRequestHeader(Content-Type, text/plain;charset=UTF-8);

// Or... whatever



// Actually sends the request to the server.

request.send(postData);