var request = null;
   
   function createRequest() {
     try {
       request = new XMLHttpRequest();
     } catch (trymicrosoft) {
       try {
         request = new ActiveXObject("Msxml2.XMLHTTP");
       } catch (othermicrosoft) {
         try {
           request = new ActiveXObject("Microsoft.XMLHTTP");
         } catch (failed) {
           request = null;
         }
       }
     }

   if (request == null)
       alert("Error creating request object!");
   }  
   
   function validateUserId() 
   {     
   createRequest();
   var code=document.getElementById("userid").value;
   if(code=="")
	{
		document.getElementById("userid").className="input_error";
		alert("Please enter the Nickname");
		document.getElementById("userid").focus();
		return false;
	}
	else if(code.length<3)
	{
		document.getElementById("userid").className="input_error";
		alert("Nickname should be minimum 3 characters");
		document.getElementById("userid").focus();
		return false;
	}
	else
	{
		value=document.getElementById("userid").value;
		var valid=/^[0-9a-zA-Z_]*$/;
		if(value!=""&& !valid.test(value))
      	{
      			document.getElementById("userid").className="input_error";
		       	alert("Nickname should contain only alphabets,digits and underscore without embedded spaces\n");
				document.getElementById("userid").focus();
				return false;
      	}
	}
   var url = "validatenick?nickname="+escape(code);
   request.open("GET", url, true);
   request.onreadystatechange = updatePage;
   request.send(null);
   }
   function updatePage() {
   if (request.readyState == 4) {
    if (request.status == 200) {
	  
	   var msg=request.responseText;
		if(msg=="invalid")
		{
	   		document.getElementById("vuser").innerHTML="Nickname already exists";
	   		document.getElementById("vuser").className = "bp_invalid";
	   		var submitBtn = document.getElementById("submit");
       		submitBtn.disabled = true;
	   	}
	   	else
	   	{
	   		document.getElementById("vuser").innerHTML="Nickname available";
	   		document.getElementById("vuser").className = "bp_valid";
	   		document.getElementById("userid").className="";
	   		var submitBtn = document.getElementById("submit");
       		submitBtn.disabled = false;
	   	}
   }
   
   }
   }