Prevent double insert at same time

using a js client side verification isn't efficient nor secure.

to prevent the form being submited twice with same data one way is to use CI4 CSRF security

set Config/Security.php $regenerate = true
put a CSRF token in your form
set a CSRF filter on your POST route or check CSRF token in your controller on POST

https://codeigniter.com/user_guide/libra...urity.html

you may also set the db column(s) as unique so if one user try to submit dupplicate data with a valid CSRF the db will not accept them