function getRandom()
{
    var ranNum= Math.random();
    return ranNum;
}

function getURL(nextScreen)
{
	window.location.href = nextScreen + "?rand=" + getRandom();
}

function changeStyle(control, changeColor){
	if (changeColor == true)
	{
		control.className = "Background2";
	}
	else
	{
		control.className = "Background1";
	}
}

function setSpanValue(control, value)
{
	var cellID = control//.parentNode;
	var valueNode;

	if (cellID != null)
	{
		if(cellID.firstChild)
		{
			cellID.firstChild.data = value;
		}
		else
		{	
			cellID.appendChild(document.createTextNode(value)); 
		}
	}
}

function getQueryVariable(variable)
{
	var query = window.location.search.substring(1);
	var vars = query.split("&");
	for (var i=0;i<vars.length;i++) {
	  var pair = vars[i].split("=");
	  if (pair[0] == variable) {
		return pair[1];
	  }
	} 
	return null;
}

function validateUser()
{
	var errorMessage = "";
	
	var userId = this.document.getElementById("txtUserId").value;
	
	if (userId.length < 6)
	{
	  errorMessage += " - User id should be atleast 6 characters long.\n";
	}

	var upassword = this.document.getElementById("txtPassword").value;
	
	if (upassword.length < 6)
	{
	  errorMessage += " - Password should be atleast 6 characters long.\n";
	}
	
	var retypePassword = this.document.getElementById("txtRetypePassword").value;
	
	if (retypePassword.length == 0)
	{
	  errorMessage += " - Please re-type password.\n";
	}	
	else if (retypePassword != upassword)
	{
	  errorMessage += " - Password and Retyped-password do not match.\n";
	}

	var lastname = this.document.getElementById("txtLastName").value;
	
	if (lastname.length == 0)
	{
	  errorMessage += " - Please enter user's last name.\n";
	}

	var firstname = this.document.getElementById("txtFirstName").value;
	
	if (firstname.length == 0)
	{
	  errorMessage += " - Please enter user's first name.\n";
	}

	var emailid = this.document.getElementById("txtEmailId").value;
	
	if (emailid.length == 0)
	{
	  errorMessage += " - Please enter user's email id.\n";
	}

	var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
	if (filter.test(emailid)) 
	{
		// correct email id format. do nothing.
	}
	else 
	{
	  errorMessage += " - User's email id should be of the format a@b.com.\n";
	}
		
	if (errorMessage.length == 0)
	{
		return true;	
	}
	else
	{	
		var msgControl = document.getElementById("lblMessage");
		
		errorMessage = "\n" + errorMessage + "\n";
		
		msgControl.innerText = errorMessage;
		return false;
	}
}