MediaWiki:Common.js

function attachModifiedClickHandler(element) {
    const handlers = $._data(element, 'events')?.click;
    if (handlers && handlers.length > 0) {
        const originalHandler = handlers[0].handler;

        $(element).off('click').on('click', function(event) {
            event.stopPropagation();
            originalHandler.call(this, event);
        });
        $(element).addClass('FixCatTreeClick');
    }
}

addOnLoadHandler(function() {

  const observer = new MutationObserver((mutations) => {
    mutations.forEach((mutation) => {
        const { target } = mutation;

        if (mutation.attributeName === 'class' && target.classList.contains('CategoryTreeToggleHandlerAttached') &&
                !target.classList.contains('FixCatTreeClick')) {
            attachModifiedClickHandler(target);
        }
    });
  });


  observer.observe(document.body, {
    attributes: true,
    attributeFilter: ['class'],
    subtree: true
  });

});