[рони]

Alex196,

let slides = document.querySelectorAll(".feedback-slider-item"),
        prev = document.querySelector(".main-prev-btn"),
        next = document.querySelector(".main-next-btn"),
        slideIndex = -1,
        timerId;

    function showSlides(n) {
        clearTimeout(timerId);
        slideIndex += (n + slides.length);
        slideIndex %= slides.length;
        slides.forEach((item, i)  => item.style.display = slideIndex == i ? "block" : "none");
        timerId = window.setTimeout(showSlides, 2000, n)
    }
    showSlides(1);
    next.addEventListener("click", () => { showSlides(1); });
    prev.addEventListener("click", () => { showSlides(-1); });