properties-dp.js

const carouselElement = document.querySelector('#carousel1');
Object.defineProperty(carouselElement, 'index', {
    set(idx) {
        // First check if it is numeric
        const numericIndex = parseInt(idx, 10);
        if (isNaN(numericIndex)) {
            return;   
        }
        // Update the internal state
        this._index = numericIndex;
        /* Perform the associated DOM operations */
        moveCarousel();        
    },
    get() {
        return this._index;
    }
});