var xmlHttp
function showExist(str){
	xmlHttp=GetXmlHttpObject()
	if(xmlHttp==null){
		alert("Browser Error")
		return
	}
	var url="db.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 || xmlHttp.readyState=="complete"){
		document.getElementById("txthint").innerHTML=xmlHttp.responseText
		if(xmlHttp.responseText=="email is already registered"){
			document.signupForm.email.value="";
		}
	}
}

function GetXmlHttpObject(){
	var xmlHttp=null;
	try{
		xmlHttp=new XMLHttpRequest();
	}catch(e){
		try{
			xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
		}catch(e){
			xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
		}
	}
	return xmlHttp;
}