var http = getXMLHTTPRequest();

function getXMLHTTPRequest() {
try {
req = new XMLHttpRequest();
} catch(err1) {
  try {
  req = new ActiveXObject("Msxml2.XMLHTTP");
  } catch (err2) {
    try {
    req = new ActiveXObject("Microsoft.XMLHTTP");
    } catch (err3) {
      req = false;
    }
  }
}
return req;
}

function sendRequest(name,email,phone,sub,msg){
	var myRand = parseInt(Math.random()*99999999);
	var modurl = "name="+name+"&email="+email+"&phone="+phone+"&sub="+sub+"&msg="+msg+"&rand="+myRand;
	var myurl = "server.php";
   	http.open("POST", myurl, true);
   	http.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
   	http.onreadystatechange = sendRequestResponse;
	http.send(modurl);
}

function sendRequestResponse(){
	if (http.readyState == 4) {
    	if(http.status == 200) {
      		var mytext = http.responseText;
      		if(mytext == "done"){
      			alert("Thank you, your message has been sent.");
      		}else{
      			alert("Error while sending your message");
      		}
		}else{
		//Error 
		}
	}else {
	//loading
  }
}