For the majority of your users, Java Script form validation will save a lot of time up front, but double-checking the data on the server remains necessary, in case the user has turned Java Script off.Form data that typically are checked by a Java Script could be: validate Form On Submit ( ) This is a main function that calls a series of subfunctions, each of which checks a single form element for compliance.We want to allow only letters, numbers and underscopes.
Next, we use the Java Script regular expression /\W/ to forbid illegal characters from appearing in usernames.
If you run a validation of the users form input before the form is submitted, there will be no wait time and redundant load on the server.
The setup and validation of radio buttons appears to be the form field that gives many webmasters the most difficulty in setting up.
In actual fact the setup of these fields is the most simple of all form fields to validate as radio buttons set one value that only needs to be tested when the form is submitted.