var xmlHttp

function checkPostcode(str) {
	if (str.length<4) { 
		document.getElementById("checkdiv").innerHTML="";
		document.getElementById("checkdiv").className="hidden";
		return;
	}
	if (str.length>=4) {
		xmlHttp=GetXmlHttpObject();
		var url="/scripts/postcode.php";
		url=url+"?q="+str;
		url=url+"&sid="+Math.random();
		xmlHttp.onreadystatechange=stateChanged;
		xmlHttp.open("GET",url,true);
		xmlHttp.send(null);
	}
}

function stateChanged() { 
	if (xmlHttp.readyState==4) {
		if (xmlHttp.responseText == "") { document.getElementById("checkdiv").className="hidden"; }
		else {
			document.getElementById("checkdiv").innerHTML=xmlHttp.responseText;
			document.getElementById("checkdiv").className="";
		}
	}
}

function GetXmlHttpObject() {
	var xmlHttp=null;
	try {
		// Firefox, Opera 8.0+, Safari
		xmlHttp=new XMLHttpRequest();
	}
	catch (e) {
		// Internet Explorer
		try {
			xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
		}
		catch (e) {
			xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
		}
	}
	return xmlHttp;
}