Add confirmation popup on “Move to Trash”

You can try to admin enqueue this script, with jquery dependency:

jQuery( function($) {       
    $('.edit-php a.submitdelete, .post-php a.submitdelete').click( function( event ) {
        if( ! confirm( 'Are you sure you want to move the post to trash?' ) ) {
            event.preventDefault();
        }           
    });
});

where we restrict the conformation on the a.submitdelete clicks to the .edit-php and .post-php body classes.

Hope you can adjust it to your needs, e.g. regarding i18n.