//check card data here
function submitForm(form)
{
	// make sure e-mail is entered
	if(!checkemail(form))
		return false
	
	
	// make sure a resource is checked
	if(!checkbox(form))
		return false
	
	return true
}

//check email address here
function checkemail(form)
{
	if (isEmail(form.youremail.value)==false)
	{
		alert("Invalid email address.");
		form.youremail.focus();
		form.youremail.select();
		return false;
	}
	if (form.youremail.value=="")
	{
		alert("Please enter your email address");
		form.youremail.focus();
		form.youremail.select();
		return false;
	}
 	return true;
}



// Check whether string s is empty.
function isEmpty(s)
{   return ((s == null) || (s.length == 0))
}

// Returns true if string s is empty or 
// whitespace characters only.
function isWhitespace (s)
{
    var whitespace = " \t\n\r";
    var i;

    // Is s empty?
    if (isEmpty(s)){return true;}

    // Search through characters one by one
    for (i = 0; i < s.length; i++)
    {   
        // Check that current character isn't whitespace.
        var c = s.charAt(i);

        if (whitespace.indexOf(c) == -1) return false;
    }

    // All characters are whitespace.
    return true;
}


// Email address must be of form a@b.c
function isEmail (s)
{   if (isEmpty(s)){return true;}
   
    // is s whitespace?
    if (isWhitespace(s)){return true;}
    
    // there must be >= 1 character before @, so we
    // start looking at character position 1 
    // (i.e. second character)
    var i = 1;
    var sLength = s.length;

    // look for @
    while ((i < sLength) && (s.charAt(i) != "@"))
    { i++
    }

    if ((i >= sLength) || (s.charAt(i) != "@")) return false;
    else i += 2;

    // look for .
    while ((i < sLength) && (s.charAt(i) != "."))
    { i++
    }

    // there must be at least one character after the .
    if ((i >= sLength - 1) || (s.charAt(i) != ".")) return false;
    else return true;
}