ProtoFormClass is a Prototype class that allows you to very easily validate the forms fields and send data in AJAX. ProtoFormClass is lightweight (only 4KB), unobtrusive and cross-browser and has been tested on Firefox, Opera, Safari, Internet Explorer 6+.
ProtoformClass is really easy to implement; it utilizes the field elements id attribute to indicate the validation requirements (through prefixes). The title attribute of the form fields (to be validated) is used to show an error message; assign an id to each of these fields with your prefix and the type of validation desired.
Developed by Filippo Buratti; ProtoFormClass is available for download under the MIT License. You can find further information, demos & download on Filippo Buratti’s Website.