function markError(theField) {
  theField.style.border="2px solid red";
}
function markValid(theField) {
  theField.style.border="";
}

function checkField(theField) {
	var error = false;
	if(empty_field(theField)) {
		error = true;
    markError(theField);
	} else {
		markValid(theField);
	}
	return error;
}

function checkEmail(theField) {
	var error = false;
	if(empty_field(theField) || mail_valid(theField) == false) {
		error = true;
    markError(theField);
	} else {
		markValid(theField);
	}
	return error;
}

function mail_valid(theField) {
  if(theField.value.indexOf('@', 0) == -1)
		return false;
  else
    return true;
}

function empty_field(theField) {
	if (theField != null) {
	  if(theField.value == "") {
	    return true;
		}
	}
}

function send_form_content(form, namesArray) {
	
	var error = false;
  for (var i = 0; i < namesArray.length; i++) {
  	var currentField = form[namesArray[i]];
  	if (currentField != null) {
	  	error = checkField(currentField);
	  	if (namesArray[i] == 'email') {
	  		error = checkEmail(currentField);
	  	}
	  } else {
	  	alert("Conf Error: Field not available: " + namesArray[i]);
	  }
  }
  if (error) {
    var fehleranzeige = $("error");
    fehleranzeige.style.visibility = "visible";
  } else {
  	fehleranzeige.style.visibility = "hidden";
  }
  return !error;
}