带有函数问题的JavaScript幻灯片

函数plusSlides在我的html中通过onclick调用。显示了我正在使用的类似函数和html。类mySlides包含将为每个n==xin showSlides显示的文本。与链接中的幻灯片演示示例不同，当我尝试单击onclick=plusSlides-1时，我的函数不起作用。例如，当我在plusSlides-1上单击三次时，会同时添加AeralMap和fedTiless，但不会添加路线图。有人知道为什么吗

function roadMap() {    
  map.addLayer(Road);
  map.removeLayer(febTiles);

}
function febTiless() {

  map.addLayer(febTiles);
  map.removeLayer(Road);

}

function aerialMap() {

  map.addLayer(Aerial);
  map.removeLayer(febTiles);
  map.removeLayer(Road);
}


var slideIndex = 1;
showSlides(slideIndex);
function plusSlides(n) {
  showSlides(slideIndex += n);
}
function currentSlide(n) {

  showSlides(slideIndex = n);
}
function showSlides(n) {

  var slides = document.getElementsByClassName("mySlides");

  if (n > slides.length) {slideIndex = 1}    
  if (n < 1) {slideIndex = slides.length}
  if(n == 1)
   aerialMap();
  if(n == 2) 
   febTiless();
  if(n == 3)
   roadMap();

  for (i = 0; i < slides.length; i++) {
      slides[i].style.display = "none";  
  }
  slides[slideIndex-1].style.display = "block";  
}

---

错误在代码的这一部分：

if (n > slides.length) {slideIndex = 1}    
if (n < 1) {slideIndex = slides.length}
if(n == 1)
  aerialMap();
if(n == 2) 
  febTiless();
if(n == 3)
  roadMap();

---

尝试添加map.removeLayerAerial；到前两个功能路线图和febTiless。可能是由于缺少这些调用，导致本应可见的图层被天线覆盖。感谢您的评论，但这并不能解决与plusSlides-1相比plusSlides-1出现故障的问题1。

var slideIndex;
showSlides(1);

function plusSlides(n) {
  showSlides(slideIndex + n); // avoid assignment here
}

function currentSlide(n) {
  showSlides(n); // avoid assignment here
}

function showSlides(n) {
  var slides = document.getElementsByClassName("mySlides");

  slideIndex = n; // assign only here, at a single place
  // Don't use n anymore, only work with slideIndex
  if (slideIndex > slides.length) {slideIndex = 1}    
  if (slideIndex < 1) {slideIndex = slides.length}
  if(slideIndex == 1)
   aerialMap();
  if(slideIndex == 2) 
   febTiless();
  if(slideIndex == 3)
   roadMap();

  for (i = 0; i < slides.length; i++) {
      slides[i].style.display = "none";  
  }
  slides[slideIndex-1].style.display = "block";  
}