var req;

function verify_subdomain() {
	req = false;
    // branch for native XMLHttpRequest object
    if(window.XMLHttpRequest && !(window.ActiveXObject)) {
    	try {
			req = new XMLHttpRequest();
        } catch(e) {
			req = false;
        }
    // branch for IE/Windows ActiveX version
    } else if(window.ActiveXObject) {
       	try {
        	req = new ActiveXObject("Msxml2.XMLHTTP");
      	} catch(e) {
        	try {
          		req = new ActiveXObject("Microsoft.XMLHTTP");
        	} catch(e) {
          		req = false;
        	}
		}
    }


	var subdomain = document.getElementById("subdomain").value;

	var subdomain_length = subdomain.length;

	var url = "/subdomain-lookup.php?subdomain=" + subdomain;
		
	if ((req) && (subdomain_length > 0)) {
		req.onreadystatechange = get_response;
		req.open("GET", url, true);
		req.send(null);
	}
}

function get_response(evt) {
   // The page has loaded and the HTTP status code is 200 OK
   if (req != null) {
	   if (req.readyState == 4) {
		  if (req.status == 200) {

			var subdomain_count = req.responseText;

			if (subdomain_count > 0) {
				// already exists;
				document.getElementById("availability_response").innerHTML = " is not available.";
			} else {
				document.getElementById("availability_response").innerHTML = " is available.";
			}
					
		 }
	  }
  }
}