validation
Using Ajax to Validate Forms
Use PHP and jQuery with some AJAX to create a form that validates the data entered.
Tutorials, demos and projects in Ajax (XMLHTTPRequest) Programming
This simple script use Ajax (Asynchronous JavaScript and XML) to allow all the links on your web pages to be automatically checked for of bad links.
javascript Form validator
Very detailed tutorial how to create java script that checks if valid entries have been put into form inputs.
AJAX Degradable Form Validation
This example demonstrates implementing efficient thread-safe AJAX techniques, and works even with browser that don't support JavaScript.
jQuery - numeric validation
Allows only valid characters (i.e. numbers) to be typed into a text box. Can take negative numbers and a decimal point. You can supply a callback that runs when focus is lost and the value in the tex ...
Live Validation - Validation as you type
A javascript library for all your client-side and form validation needs.