Ajax loaded form elements for post-edit screen

I want to load some form elements for a custom post type’s edit screen via AJAX.

What’s the best practice to implement this?

Should I use this algorithm?

Hook an action to admin_menu to

detect the request from AJAX client (via x-requested-with),

clean the buffer (via ob_clean),

output the requested element, and exit.

Request wp-admin/post-new.php from AJAX client