However, the test will be performed in server code.You can control how validation errors are displayed by defining CSS classes that have the following reserved names: .
Users get immediate feedback, which is convenient for them.Form validation normally used to occur at the server, after the client had entered all the necessary data and then pressed the Submit button.If the data entered by a client was incorrect or was simply missing, the server would have to send all the data back to the client and request that the form be resubmitted with correct information.For example, here's what the page looks like if you forget to enter a course name, if you enter an, and if you enter an invalid date: By default, user input is validated after users submit the page — that is, the validation is performed in server code.A disadvantage of this approach is that users don't know that they've made an error until after they submit the page.The CSS rules that end in to both have the same fixed size.
That way, the display area for the field is static and won't change the page flow if an error message is displayed.
Client-based validation can also reduce the number of times that the user has to submit the form to correct multiple errors.
Note Even if you use client-side validation, validation is always also performed in server code.
This was really a lengthy process which used to put a lot of burden on the server.
Java Script provides a way to validate form's data on the client's computer before sending it to the web server. First let us see how to do a basic form validation.
These pairs let you define rules for both conditions: an error condition and a "normal" (non-error) condition.