How to check if I am in admin_ajax?

Question

Right now for my plugin, I am using in_admin() to determine if the user is in the frontend of the site or in the admin area. However, the problem occurs when plugins use admin_ajax.php to process ajax requests.

I need a way to register hooks and plugins only when processing admin_ajax.php or in the frontend of the site. What is the best way to go about doing that?

Answer 1

Check the constant DOING_AJAX. Its definition is the first working code in wp-admin/admin-ajax.php.

Example:

if ( defined( 'DOING_AJAX' ) && DOING_AJAX )
{
    // do something
}