How to check existing data with jquery validation library with codeigniter 4 csrf?

 Thank you very much. I corrected  with your suggestion. but my problem now is  how I can update csrf on jqery remote object " remote:{ data:{} } "?

I don't understand the essence of the problem.
I don't know how the library works, but I assume that you already have some code that overwrites the csrf hash.

Code:

complete: function(data){
   $('input[name="csrf_hash_name"]').val(data.csrf);
}

and the value of the csrf_hash_name key in the "data" object is computed on every request.

Just send data

PHP Code:

return $this->response->setJSON([
    'status' => ! (bool) $count, // convert number to boolean and invert ( 0 = true; > 0 = false)
    'csrf' => csrf_hash()
]); 


Receiving data

Code:

complete: function(data){
    $('input[name="csrf_hash_name"]').val(data.csrf);
    return data.status;
}