Dry When Validating Calculations Made Client Side (javascript) On The Server (php)

I'm looking to DRY when I am validating a calculation made by the client (javascript) back on the server (PHP). I'm validating on the server to prevent a malicious user from dupin

Solution 1:

Client-side validation is all about saving the user time. By not having to send bad data to the server and then having the request rejected, we can save loading time.

Server-side validation is about security. We need to make sure that the data we get on the server is valid and not going to cause us any problems.

So in my opinion, it's best to write the code twice and not to use AJAX requests to validate data unless you have to