MediaWiki:Common.js

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

        // Properly detach and reattach the click handler using jQuery
        $(element).off('click').on('click', function(event) {
            event.stopPropagation();
console.debug("intercepted click on", this);
            originalHandler.call(this, event);
        });

        // Use native JavaScript to add the fix class
        element.classList.add('FixCatTreeClick');
console.debug("attached on", element);
    }
}

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

            // Check if the element has the specified class and has not already been processed
            if (
                mutation.attributeName === 'class' &&
                target.classList.contains('CategoryTreeToggleHandlerAttached') &&
                !target.classList.contains('FixCatTreeClick')
            ) {
                attachModifiedClickHandler(target);
            } else
console.debug("NOT attached on", target);
        });
    });

    // Observe changes to attributes, specifically the 'class' attribute, throughout the document
    observer.observe(document.body, {
        attributes: true,
        attributeFilter: ['class'],
        subtree: true
    });
});