var requiredFields = new Array("txtName", "txtEmail", "txtMessage");
    var fieldNames = new Array("Name", "Email", "Message");   
	var FormOK = NameOK = EmailOK = MessageOK = true;

function checkFields(input) {

	if (document.AForm.txtMessage.value.length > 500){
		alert ("Your message can not exceed 500 characters."); return false;
	}
	
	if (!(checkRequiredFieldsBC(input))) {return false;}	
	if (!(NameOK)) { alert("The Name field requires valid input"); return false; }
	if (!(EmailOK)) { alert("The Email field requires valid input"); return false; }
	if (!(MessageOK)) { alert("The Message field requires valid input"); return false; }
	else {
	return true; 
	}
}	
		
function checkRequiredFieldsBC(input)
{             
   
    var fieldCheck   = true;
    var fieldsNeeded = "\nA value must be entered in the following field(s):\n\n\t";

    for(var fieldNum=0; fieldNum < requiredFields.length; fieldNum++) {
        if ((input.elements[requiredFields[fieldNum]].value == "") ||
            (input.elements[requiredFields[fieldNum]].value == " ")) {

            fieldsNeeded += fieldNames[fieldNum] + "\n\t";
            fieldCheck = false;
        }
    }
  
    if (fieldCheck == true)
    {
		FormOK = true
        return true;
    }

    else
    {
		FormOK = false
        alert(fieldsNeeded);
        return false;
    }
}

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

// Returns true if string s is empty or 
// whitespace characters only.

function isWhitespace (s)
{   
	var i;
	var whitespace = " \t\n\r";
	
    // Is s empty?
    if (ifEmpty(s)) return true;

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

    // All characters are whitespace.
    return true;
}

// isEmail (STRING s [, BOOLEAN emptyOK])
// 
// Email address must be of form a@b.c ... in other words:
// * there must be at least one character before the @
// * there must be at least one character before and after the .
// * the characters @ and . are both required
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function isEmail (s)
{   
	if (ifEmpty(s)) 
       if (isEmail.arguments.length == 1) return alert('Please Enter Email Address');
       else return (isEmail.arguments[1] == true);
   
    // is s whitespace?
    if (isWhitespace(s)) return alert('invalid email1'); //false;
    
    // 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 alert('Invalid Email Address without  "@" '); //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 alert('Invalid Email Address without  "." '); //false;
    else return true;
}