javascript - css 动画无法与 javascript 代码一起使用

Question

我正在尝试制作一个基于 w3 css 的带有淡入淡出动画的自动 Javascript 幻灯片，当您点击箭头时，该幻灯片会切换到手动。除此之外，在开始时，如果未单击上一个或下一个箭头，幻灯片将循环运行 2 次。在幻灯片播放完 2 个循环之前单击上一个或下一个箭头也会将幻灯片切换为手动。

问题出在 W3 CSS 淡入淡出动画上。如果我保留它，在自动循环结束时，幻灯片会不断淡入和淡出，而它应该保持静态。因此，我必须使用以下代码删除淡入淡出动画 -

 Array.prototype.forEach.call(x, function(element) {
     element.classList.remove("w3-animate-fading"); //remove the fading
     });

请指出我做错了什么，动画无法正常使用 javascript(请注意 - 我是 Javascript 新手)。这是完整的片段，包括删除动画代码 -

var index = 1;
var paused = false;
var slideShow = [];
var counter = 0;
var maxLength = 0;
var loops = 2;
var interval = 2000; //for testing purposes

 var x = document.getElementsByClassName("slideShow");
 maxLength = x.length * loops; //times 2 for two loops
 
for (i=0; i<x.length; i++) {
  slideShow[i] = document.getElementsByClassName("slideShow")[i];
  slideShow[i].style.display = "none";
}

slideShow[0].style.display = "block";

var slides = setInterval(function() {
counter++; //adding counter
   if (counter <= maxLength) //ie counter <= 10, execute 
  {
    if (index < slideShow.length) {
  
    index++;
		showDivs();
    
    }
  else {
		index = 1;
		showDivs();
	  }
  }
      Array.prototype.forEach.call(x, function(element) {
     element.classList.remove("w3-animate-fading"); //remove the fading
     });
 },interval);

function control(n) {
  clearInterval(slides);

  if (index+n > slideShow.length) {
    index = 1;
  }
  else if (index+n <= 0) {
    index = slideShow.length;
  }
  else {
		index += n;
  }
  showDivs();
}

function showDivs() {
  //Hide all slideShow elements, and then show only the targeted element
  for (i=1; i<=slideShow.length; i++) {
    slideShow[i-1].style.display = "none";
  }
  slideShow[index-1].style.display = "block";
}

.w3-content.w3-display-container {
  margin-top: 100px;
}
 
 button.w3-button.w3-display-left.w3-black {
  position: relative;
  left: -50px;
}
 
 button.w3-button.w3-display-right.w3-black {
  position: relative;
  right: -118px;
}

<link href="https://www.w3schools.com/w3css/4/w3.css" rel="stylesheet"/>
<div class="w3-content w3-display-container " style="max-width:150px">

  <div class="w3-display-container w3-animate-fading slideShow">
      <a href="" 	target="_blank" title="slide1">
      <img class="" src="img01.jpg"	style="width:100%">
      </a>
      <div class="w3-display-bottomleft w3-large 	w3-container w3- padding-16 w3-black">
        <a href="" target="_blank" title="slide1">Slide-1 (read more)</a>
    </div>
  </div>

  <div class="w3-display-container w3-animate-fading slideShow">
        <a href="" target="_blank" title="slide2">
    <img class="" src="img02.jpg" style="width:100%">
    </a>	
    <div class="w3-display-bottomright w3-large w3-container w3-padding-16     w3-black">
        <a href="" target="_blank" title="slide2">Slide-2 (more)</a>
    </div>
  </div>

  <div class="w3-display-container w3-animate-fading slideShow">
        <a href="" target="_blank" title="slide3">
    <img class="" src="img03.jpg" style="width:100%">
    </a>
        <div class="w3-display-topleft w3-large w3-container 
           w3-padding-16 w3-black">
        <a href="" target="_blank" title="slide3">Slide-3 (read more)</a>
        </div>
  </div>  

  <div class="w3-display-container w3-animate-fading slideShow">
        <a href="" target="_blank" title="slide4">
    <img class="" src="img04.jpg" style="width:100%">
    </a>
        <div class="w3-display-topright w3-large w3-container 
           w3-padding-16 w3-black">
        <a href="" target="_blank" title="slide4">Slide-4 (read more)</a>
        </div>
  </div>

  <div class="w3-display-container w3-animate-fading slideShow">
      <a href="" target="_blank" title="slide5">
      <img class="" src="img05.jpg" style="width:100%">
      </a>
        <div class="w3-display-middle w3-large w3-container  	
           w3-padding-16 w3-black">
        <a href="" target="_blank" title="slide5">Slide-5 (read	more)</a>
        </div>
  </div>

  <button class="w3-button w3-display-left w3-black" onclick="control(-1)"><</button>
      <button class="w3-button w3-display-right w3-black" onclick="control(1)">></button>

</div>

Answer 1

删除这个，

 Array.prototype.forEach.call(x, function(element) {
 element.classList.remove("w3-animate-fading"); //remove the fading
 });

并有条件地添加和删除事件幻灯片的淡入淡出类，

slideShow[0].className = "w3-animate-fading slideShow";
slideShow[index-1].className = "w3-animate-fading slideShow";

查看代码片段

var index = 1;
var paused = false;
var slideShow = [];
var counter = 0;
var maxLength = 0;
var loops = 2;
var interval = 2000; //for testing purposes

 var x = document.getElementsByClassName("slideShow");
 maxLength = x.length * loops; //times 2 for two loops
 
for (i=0; i<x.length; i++) {
  slideShow[i] = document.getElementsByClassName("slideShow")[i];
  slideShow[i].style.display = "none";
}

slideShow[0].style.display = "block";
slideShow[0].className = "w3-animate-fading slideShow";

var slides = setInterval(function() {
counter++; //adding counter
   if (counter <= maxLength) //ie counter <= 10, execute 
  {
    if (index < slideShow.length) {
  
    index++;
		showDivs();
    
    }
  else {
		index = 1;
    // Here add the parameter for identify loop ends
		showDivs(true);
	  }
  }
     
 },interval);

function control(n) {
  clearInterval(slides);

  if (index+n > slideShow.length) {
    index = 1;
  }
  else if (index+n <= 0) {
    index = slideShow.length;
  }
  else {
		index += n;
  }
  showDivs();
}

function showDivs(value) {
  //Hide all slideShow elements, and then show only the targeted element
  for (i=1; i<=slideShow.length; i++) {
    slideShow[i-1].style.display = "none";
  }
  slideShow[index-1].style.display = "block";
  
  if(value) { // Here check the condition if loop ends remove fade class from slide
  
      slideShow[index-1].classList.remove("w3-animate-fading");
      
  } else {  // otherwise add fade class to slide
         
      slideShow[index-1].className = "w3-animate-fading";
      
       // after that remove class after some time for remove fade
      setTimeout(function(){
          slideShow[index-1].classList.remove("w3-animate-fading");
      },1000);
  }
}

.w3-content.w3-display-container {
  margin-top: 100px;
}
 
 button.w3-button.w3-display-left.w3-black {
  position: relative;
  left: -50px;
}
 
 button.w3-button.w3-display-right.w3-black {
  position: relative;
  right: -118px;
}

<link href="https://www.w3schools.com/w3css/4/w3.css" rel="stylesheet"/>
<div class="w3-content w3-display-container " style="max-width:150px">

  <div class="w3-display-container w3-animate-fading slideShow">
      <a href="" 	target="_blank" title="slide1">
      <img class="" src="img01.jpg"	style="width:100%">
      </a>
      <div class="w3-display-bottomleft w3-large 	w3-container w3- padding-16 w3-black">
        <a href="" target="_blank" title="slide1">Slide-1 (read more)</a>
    </div>
  </div>

  <div class="w3-display-container w3-animate-fading slideShow">
        <a href="" target="_blank" title="slide2">
    <img class="" src="img02.jpg" style="width:100%">
    </a>	
    <div class="w3-display-bottomright w3-large w3-container w3-padding-16     w3-black">
        <a href="" target="_blank" title="slide2">Slide-2 (more)</a>
    </div>
  </div>

  <div class="w3-display-container w3-animate-fading slideShow">
        <a href="" target="_blank" title="slide3">
    <img class="" src="img03.jpg" style="width:100%">
    </a>
        <div class="w3-display-topleft w3-large w3-container 
           w3-padding-16 w3-black">
        <a href="" target="_blank" title="slide3">Slide-3 (read more)</a>
        </div>
  </div>  

  <div class="w3-display-container w3-animate-fading slideShow">
        <a href="" target="_blank" title="slide4">
    <img class="" src="img04.jpg" style="width:100%">
    </a>
        <div class="w3-display-topright w3-large w3-container 
           w3-padding-16 w3-black">
        <a href="" target="_blank" title="slide4">Slide-4 (read more)</a>
        </div>
  </div>

  <div class="w3-display-container w3-animate-fading slideShow">
      <a href="" target="_blank" title="slide5">
      <img class="" src="img05.jpg" style="width:100%">
      </a>
        <div class="w3-display-middle w3-large w3-container  	
           w3-padding-16 w3-black">
        <a href="" target="_blank" title="slide5">Slide-5 (read	more)</a>
        </div>
  </div>

  <button class="w3-button w3-display-left w3-black" onclick="control(-1)"><</button>
      <button class="w3-button w3-display-right w3-black" onclick="control(1)">></button>

</div>