Form and inputs - ajax vs client side validation [closed]

1. What is an advantage of client-side form validation as compared to server-side?
2. Why should both client-side and server-side data validation be applied in the form?
3. What is the need of form validation in the client-side script than in the server-side programming?

What is an advantage of client-side form validation as compared to server-side?

In general, it is best to perform input validation on both the client side and server side. Client-side input validation can help reduce server load and can prevent malicious users from submitting invalid data. However, client-side input validation is not a substitute for server-side input validation.

Why should both client-side and server-side data validation be applied in the form?

Your apps should always perform security checks on any form-submitted data on the server-side as well as the client-side, because client-side validation is too easy to bypass, so malicious users can still easily send bad data through to your server.

What is the need of form validation in the client-side script than in the server-side programming?

If the user request does not require any server resources to validate the input , you can use Client Side Validation. In the Server Side Validation, the input submitted by the user is being sent to the server and validated using one of server side scripting languages such as ASP.Net, PHP etc.