滑块工作正常，但暂停不是

Question

有人知道这里有什么问题吗？想要在鼠标悬停时暂停滑块。我无法弄清楚它有什么问题。滑块工作，但它不会暂停。

function showDivs(n) {
  var i;
  var x = document.getElementsByClassName("mySlides");
  if (n > x.length) {slideIndex = 1}
  if (n < 1) {slideIndex = x.length}
  for (i = 0; i < x.length; i++) {
     x[i].style.display = "none";
  }
  x[slideIndex-1].style.display = "block";
}

var slideIndex = 0;
var timer = null;
carousel();

function carousel() {
    var i;
    var x = document.getElementsByClassName("mySlides");
    for (i = 0; i < x.length; i++) {
      x[i].style.display = "none";
    }
    slideIndex++;
    if (slideIndex > x.length) {slideIndex = 1}
    x[slideIndex-1].style.display = "block";

    var timer = setTimeout(carousel, 1000);
    mouseOver = clearTimeout(timer);
    mouseOut = setTimeout(carousel, 1000);
}

var slideIndex = 1;
showDivs(slideIndex);

function plusDivs(n) {
  showDivs(slideIndex += n);
}