function makeRequest(docElementId, postString) {
        var httpRequest;
       
       if (window.XMLHttpRequest) { // Mozilla, Safari, ...
            httpRequest = new XMLHttpRequest();
            if (httpRequest.overrideMimeType) {
                httpRequest.overrideMimeType('text/xml');
                // See note below about this line
            }
        } 
        else if (window.ActiveXObject) { // IE
            try {
                httpRequest = new ActiveXObject("Msxml2.XMLHTTP");
                } 
                catch (e) {
                           try {
                                httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
                               } 
                             catch (e) {}
                          }
                                       }

        if (!httpRequest) {
            alert('Giving up :( Cannot create an XMLHTTP instance');
            return false;
        }
        httpRequest.onreadystatechange = function() { returnResult(httpRequest, docElementId); };
       	httpRequest.open('POST', '/js/ajax_function.php' , true);
       	httpRequest.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
        httpRequest.send(postString);
    }

    function returnResult(httpRequest, docElementId) {
        var  result = '';

        if (httpRequest.readyState == 4) {
        	
            if (httpRequest.status == 200) {
             result = httpRequest.responseText;

			if(result == 'null')
				document.getElementById(docElementId).innerHTML = '';
			else
				document.getElementById(docElementId).innerHTML = result;
            } else {
                alert('There was a problem with the request.');
            }
        }	
    }