function validateEmail(fieldvalue){
    	if(fieldvalue == null || fieldvalue.length ==0){        
    		return false;    
	}else{
        	return true;
        }
}

function validateField(fieldvalue){    
	if(fieldvalue == null|| fieldvalue.length ==0){
	        return false;    
	}    
	return true;
}

function nl2br(text){
    return text.replace(/(\r\n)|(\n)/g,"<br />");
}

function getXMLHRObject(){
    var ajaxRequest;
    try{        
    	ajaxRequest = new XMLHttpRequest();    
    } catch (e){        
    	try{
    	ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
    	} catch (e) {
    	    try{
    	    ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
    	    } catch (e){
    	    alert("Please update your browser!");
    	    return false;
    	    }
        }
    }
    return ajaxRequest;
}

function checkExistingUser(){ 
	ajaxRequest = getXMLHRObject();
	ajaxRequest.onreadystatechange = function(){
	       if(ajaxRequest.readyState == 4){            
	       document.getElementById("unexist").className=ajaxRequest.responseText;        
	       }    
	}   
	var un = document.getElementById('email').value;    
        ajaxRequest.open("GET", "./checkUser.php?un="+un, true);    
        ajaxRequest.send(null);
}