// JavaScript Document


// Check whether string s is empty.
// whitespace characters only.
function isEmpty()
{	
	if (document.formQuestions.Name.value.length == 0)
	{	document.formQuestions.Name.focus();	
		return true;
	}
	else if (document.formQuestions.sn.value.length == 0)
	{	document.formQuestions.sn.focus();	
		return true;
	}
	else if (document.formQuestions.mail.value.length == 0)
	{	document.formQuestions.mail.focus();	
		return true;
	}
	else if (document.formQuestions.address.value.length == 0)
	{	document.formQuestions.address.focus();	
		return true;
	}
	else if (document.formQuestions.problem.value.length == 0)
	{	document.formQuestions.problem.focus();	
		return true;
	}
	else return false;
}	

function isWhitespace (s)
{   var i;
	// Search through string's characters one by one
    // until we find a non-whitespace character.
    // When we do, return false; if we don't, return true.
	for (i = 0; i < s.length; i++)
    {   // Check that current character isn't whitespace.
        var c = s.charAt(i);
        if (c.indexOf(" ") > -1) return true;
	}
	// All characters are whitespace.
    return false;
}

function isEmail(s)
{   // is s whitespace?
    if (!isWhitespace(s))
	{	// 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;
	}
	return false;
}

function check(s)
{	var returnValue = true;
	if (isEmpty())
	{	alert("Please fill all required text fields");
		returnValue = false;
	}
	else
	{	if (!isEmail(s))
		{	alert("Please enter valid email address");
			document.formQuestions.mail.focus();
			returnValue = false;
		}
	}
	return returnValue;
}