var http=createHttp();
var url = "checkusername.php"

function createHttp() {
	if (window.XMLHttpRequest){
		return new XMLHttpRequest()
	}
	else if (window.ActiveXObject){
		return new ActiveXObject("Microsoft.XMLHTTP")
	}
}

function validateusername() {
	$('ajaximgid').src = "images/ajax/search.gif";
	var username=$('usernameid').value;

	http.onreadystatechange=checkusername;
	http.open("GET",url+"?username="+username,true);
	http.send(null);
}

function $(obj) {
	return document.getElementById(obj);
}

function checkusername() {
	if (http.readyState==4){
		if (http.status==200) {
			var res = http.responseText;
			if(res == 1) {
				$('ajaximgid').src = "images/ajax/yes.gif";
			}
			else if(res == 0 ) {
				$('ajaximgid').src = "images/ajax/no.gif";
			}
			else if(res == -1 ) {
				$('ajaximgid').src = "images/ajax/spacer.gif";
				alert("ERROR: Blank username or invalid charactor in the username.\rPlease try again.");
				$('usernameid').focus();
			}
		}
		else{
			alert("Problem retrieving XML data")
		}
	}
}