MediaWiki:Common.js

mw.hook( 'wikipage.categories' ).add( function ( $content ) {
$('.CategoryTreeToggle.CategoryTreeToggleHandlerAttached').each(function() {
    const handlers = $._data(this, 'events').click;
    
    if (handlers && handlers.length > 0) {
        const originalHandler = handlers[0].handler;

        $(this).off('click').on('click', function(event) {
            event.stopPropagation();
   console.log("intercepted handler");
            originalHandler.call(this, event);
        });
    }
});

});