var notValidChars = "'&?*^%$#@|\/+=-[]}{};:<>, ";

function validate_alpha(entered,alertbox)
{
validateFlag=true;
for (j=0; j<entered.value.length; j++)
	{
    toCheck=entered.value.charAt(j);
	if (notValidChars.indexOf(toCheck)>=0)
		validateFlag=false;
	} 
if (!validateFlag)
	alert(alertbox);
return validateFlag;
}

function trim(strVariable)
{

if (strVariable==null)
	return "";
var len=strVariable.length;
if (len==0)
	return "";
	
// first part:  trims blanks to the right
var index=len-1;
while ((index>0) && (strVariable.charAt(index)==" ")) index--;
strVariable=strVariable.substring(0,index+1);

// second part:  trims leading blanks

len=strVariable.length;
index=0;
while ((index<len) && (strVariable.charAt(index)==" ")) index++;
strVariable=strVariable.substring(index,len);
return strVariable;
}

function emptyvalidation(entered, alertbox)
{
with (entered)
	{
    value=trim(value);
	if (value==null || value=="")
		{	
		if (alertbox!="") 
			{
			alert(alertbox);
			} 
		return false;
		}
	else 
		{
		return true;
		}
	}
}

var bCheckMandatory=true;

function validateFields()
{
var ok=true;
if (bCheckMandatory==true)
	{
	ok= emptyvalidation(document.dropdownmenu.username,'You must enter a username in the space provided')
	if (ok)
		if (document.dropdownmenu.username.value.length<4)
		{
		alert ("Your username must be at least 4 characters long...");
		ok=false;
		}
	if (ok)
		ok= emptyvalidation(document.dropdownmenu.password,'You must enter a username in the space provided.')
	if (ok)
		if (document.dropdownmenu.password.value.length<5)
		{
		alert ("Your password must be at least 5  characters long...");
		ok=false;
		}
	}
	if (ok)
		ok=validate_alpha(document.dropdownmenu.username,"Invalid characters in User name...(Please use only letters and numbers)");
	if (ok)
		ok=validate_alpha(document.dropdownmenu.password,"Invalid characters in password...(Please use only letters and numbers)");
return ok;
}

//verify if the text is numeric
function IsNumeric(strString)
   //  check for valid numeric strings	
   {
   var strValidChars = "0123456789.";
   var strChar;
   var blnResult = true;

   if (strString.length == 0) return false;

   //  test strString consists of valid characters listed above
   for (i = 0; i < strString.length && blnResult == true; i++)
      {
      strChar = strString.charAt(i);
      if (strValidChars.indexOf(strChar) == -1)
         {
         blnResult = false;
         }
      }
   return blnResult;
   }