JavaScript Form Validation
Any interactive web site has form input. If you run a validation of the user's form input before the form is submitted, there will be no wait time and redundant load on the server. "Bad data" are already filtered out when input is passed to the server-based program. It also allows to simplify server-based program. Client side form validation usually done with javascript. For the majority of your users, JavaScript form validation will save a lot of time up front.