function ajaxRequest()
{
var opt = 's=whatever you want to pass';
var page = 'ajax_page.php';
var http = createRequestObject();
http.onreadystatechange = function()
{
if((http.readyState == 4) && (http.status == 200))
{
var text = http.responseText;
}
}
http.open('POST', page, true);
http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
http.setRequestHeader("Content-length", opt.length);
http.setRequestHeader("Connection", "close");
http.send(opt);
}