carousel.js

let slideIndex = 1;
    showSlides(slideIndex);

    // Next/previous controls
    function plusSlides(n) {
      showSlides((slideIndex += n));
    }

    // Thumbnail image controls
    function currentSlide(n) {
      showSlides((slideIndex = n));
    }

    function showSlides(n) {
      let i;
      let slides = document.getElementsByClassName("mySlides");
      let dots = document.getElementsByClassName("dot");
      if (n > slides.length) {
        slideIndex = 1;
      }
      if (n < 1) {
        slideIndex = slides.length;
      }
      for (i = 0; i < slides.length; i++) {
        slides[i].style.display = "none";
      }
      for (i = 0; i < dots.length; i++) {
        dots[i].className = dots[i].className.replace(" active", "");
      }
      slides[slideIndex - 1].style.display = "block";
      dots[slideIndex - 1].className += " active";
    }