How to prevent users from entering invalid characters inside an input field

Question

Given a text input field. How can I prevent users from entering spaces, and other other than letters numbers or dashes (-).

Alphanumerics only - \"The alphanumeric

Answer 1

There are plenty of Javascript validation libraries out there. A quick Google search for 'javascript validation' produced the JQuery Validation plugin plugin as the first hit, so that's probably a good place to start.

As @Chris Cooper said, make sure that you also do server-side validation, because it's pretty trivial for a user to turn off javascript and avoid your client-side validation rules.