// whitespace characters
var whitespace = " \t\n\r";



//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 i;

  // Is s empty?
  if (isEmpty(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;
}


function isValidEmail(s){
  // is s whitespace?
  if(s == '')
    return 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 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;
}



// Checks to see if a required field is blank.  If it is, a warning
// message is displayed...
function ForceEntry(objField, FieldName){
  var strField = objField.value;

  if(isWhitespace(strField)){
    alert("You need to enter information for (  " + FieldName + " ) as this is a required field.");
    objField.focus();
    return false;
  }
  return true;
}


function ForceEmail(field, FieldName){
  if(!isValidEmail(field.value)){
    alert("You need to enter valid Email Address for ( " + FieldName + ").");
    field.focus();
    return false;
  }

  return true;
}