Javascript picture slider would not work on iOS

When urgent the buttons to alter picture on iOS nothing occurs. On Chrome and Android it really works as anticipated.

I’ve tried so as to add eventListener touchstart, rearranged variables (scope) and misc. different issues however I can not get it to work.

if (doc.querySelector(".slider-img-container") !== null) {
  const prev = doc.querySelector(".prev");
  const subsequent = doc.querySelector(".subsequent");
  const pictures = doc.querySelector(".slider-img-container").kids;
  const totalImages = pictures.size;
  let index = 0;
  if (pictures.size > 1) {
    prev.addEventListener("click on", () => {
      nextImage("subsequent");
    });
    subsequent.addEventListener("click on", () => {
      nextImage("prev");
    });
    prev.addEventListener("touchstart", () => {
      nextImage("subsequent");
    });
    subsequent.addEventListener("touchstart", () => {
      nextImage("prev");
    });
  }
  operate nextImage(route) {
    if (route === "subsequent") {
      index++;
      if (index === totalImages) {
        index = 0;
      }
    } else {
      if (index === 0) {
        index = totalImages - 1;
      } else {
        index--;
      }
    }
    for (let i = 0; i < pictures.size; i++) {
      pictures[i].classList.take away("exhibiting");
    }
    pictures[index].classList.add("exhibiting");
  }
}

Thanks upfront for any assist!

Added eventlisteners, . The buttons nonetheless do not do something on iOS.