In addition, each of the fields should have a unique name.Use the following table to assign names to all of your form elements.Because the code is stored within the page or within a linked file, it is downloaded into the browser when a user accesses the page and, therefore, doesn't require a roundtrip to the server.
However, client-side validation may not work in all instances.
A user may have a browser that doesn't support client-side scripting or may have scripting disabled in the browser.
You need a custom function that you can later connect to the form.
For more information about creating a function, see JScript Functions.
In addition, this article assumes a general understanding of HTML and Java Script, although a thorough understanding is not required.
For more information about HTML and Web scripting, see one or more of the following references.
Server-side validation incorporates code validation into a form handler. NET application on the server that provides the functionality that your form needs for processing after a customer has submitted it.
Because the code is stored on the server, server-side validation requires a roundtrip to the server.
In order to access your form fields in code, you need to assign names to the form and each of the fields. For more information see, NAME Attribute | name Property.