How to make data confidential and readonly?

I am entering comments.

<div class="comment-input" contenteditable></div>

      

        
        
        
      

    

Inside the keydown event, I want to define what type of new comment is? In my example, there are 2 types: New comment and Reply comment.

My idea: add attribute comment-level

to div. For example:

<div class="comment-input" data-comment-level="0" contenteditable></div>

      

        
        
        
      

    

or

$('.sub-comment [contenteditable]').data('comment-level', 1);

      

        
        
        
      

    

If comment-level

- 0

, this is a new comment. Otherwise, he replies to the comment.

Problem: Both can be easily edited on the client side. While clicking F12

to edit an attribute on a tab Elements

or tab Console

, try typing:

// you are hacked
$('.sub-comment [contenteditable]').data('comment-level', 'foo');

      

        
        
        
      

    

My question is, how can I securely install / retrieve data?