Minimal JS to implement bootstrap carousel

bootstrap-carousel.js

var global = {
  carousels: [],
  slide: 0,
};

function nextSlide() {
  console.log("nextSlide", global);
  global.carousels[global.slide].classList.toggle("active");

  global.slide++;
  if (global.slide > global.carousels.length - 1) {
    global.slide = 0;
  }

  global.carousels[global.slide].classList.toggle("active");
}

global.carousels = document.getElementsByClassName("carousel-item");
if (global.carousels.length > 0) {
  window.setInterval(nextSlide, 3000);
}