上一个按钮导致幻灯片消失

  • Z时代
  • 2024-01-10
  • 分类：问答

我已经采取了一个简单的w3学校幻灯片，编辑here由用户Sinisake和编辑样式删除幻灯片计数器和标题，并编辑prev和下一个按钮，占用每一半幻灯片的一侧，光标改变以指示点击。上一个按钮导致幻灯片消失

唯一的问题是，当您单击第一张幻灯片上的“上一张”时，previousElementSibling会调用不存在的元素，整个幻灯片将消失。我知道这是因为我改变了前一个和下一个位置，但我不知道为什么。

此外，我隐藏点：无，但如果我从HTML和JavaScript中删除它们，幻灯片放映。

我知道一些关于CSS和html的知识，但在JavaScript中很新，所以我很感谢大家的耐心和帮助。

我的代码的下方，并且页面也在这里举办：http://dominicfortunato.com/Template%20Studio%20Site/index-updated-slideshow-2.html

(function() {  
    init(); //on page load - show first slide, hidethe rest  
    function init() {  
    parents = document.getElementsByClassName('slideshow-container');  
    for (j = 0; j < parents.length; j++) {  
     var slides = parents[j].getElementsByClassName("mySlides");  
     var dots = parents[j].getElementsByClassName("dot");  
     slides[0].classList.add('active-slide');  
     dots[0].classList.add('active');  
    }  
    }  
    dots = document.getElementsByClassName('dot'); //dots functionality  
    for (i = 0; i < dots.length; i++) {  
    dots[i].onclick = function() {  
     slides = this.parentNode.parentNode.getElementsByClassName("mySlides");  
     for (j = 0; j < this.parentNode.children.length; j++) {  
     this.parentNode.children[j].classList.remove('active');  
     slides[j].classList.remove('active-slide');  
     if (this.parentNode.children[j] == this) {  
      index = j;  
     }  
     }  
     this.classList.add('active');  
     slides[index].classList.add('active-slide');  
    }  
    }  
//prev/next functionality  
    links = document.querySelectorAll('.slideshow-container a');  
    for (i = 0; i < links.length; i++) {  
    links[i].onclick = function() {  
     current = this.parentNode;  
     var slides = current.getElementsByClassName("mySlides");  
     var dots = current.getElementsByClassName("dot");  
     curr_slide = current.getElementsByClassName('active-slide')[0];  
     curr_dot = current.getElementsByClassName('active')[0];  
     curr_slide.classList.remove('active-slide');  
     curr_dot.classList.remove('active');  
     if (this.className == 'next') {  
     if (curr_slide.nextElementSibling.classList.contains('mySlides')) {  
      curr_slide.nextElementSibling.classList.add('active-slide');  
      curr_dot.nextElementSibling.classList.add('active');  
     } else {  
      slides[0].classList.add('active-slide');  
      dots[0].classList.add('active');  
     }  
     }  
     if (this.className == 'prev') {  
    \t \t if (curr_slide.previousElementSibling.classList.contains('mySli‌​des')) {  
      curr_slide.previousElementSibling.classList.add('active-slide');  
      curr_dot.previousElementSibling.classList.add('active');  
     } else {  
      slides[slides.length - 1].classList.add('active-slide');  
      dots[slides.length - 1].classList.add('active');  
     }  
     }  
    }  
    }  
})();

/* Slideshow container */  
.slideshow-container {  
    max-width: 80%;  
    position: relative;  
    padding-top: 3%;  
    padding-bottom: 2%;  
    margin: auto;  
}  
/* Next & previous buttons */  
.prev, .next {  
    cursor: url('Images/arrow.png'), w-resize;  
    float: left;  
    position: absolute;  
    width: 50%;  
    height: 90%;  
    margin-right: auto;  
    margin-left: auto;  
    transition: 0.3s ease;  
    border-radius: 0 0px 0px 0;  
}  
/* Position the "next button" to the right */  
.next {  
    cursor: url('Images/arrow.png'), e-resize;  
    right: 0;  
    border-radius: 0px 0 0 0px;  
}  
/* On hover, add a black background color with a little bit see-through */  
.prev:hover, .next:hover {  
    background-color: rgba(0,0,0,0);  
}  
.mySlides {  
    display:none;  
}  
.active-slide {  
    display:block;  
}  
.active-slide-1 {  
    display:block;  
}  
.dot {  
    cursor:pointer;  
    height: 13px;  
    width: 13px;  
    margin: 0 2px;  
    background-color: #bbb;  
    border-radius: 50%;  
    display: none;  
    transition: background-color 0.6s ease;  
}  
.active, .dot:hover {  
    background-color: #717171;  
}  
/* Fading animation */  
.fade {  
    -webkit-animation-name: fade;  
    -webkit-animation-duration: 0.2s;  
    animation-name: fade;  
    animation-duration: 0.2s;  
}  
@-webkit-keyframes fade {  
    from {opacity: .1}  
    to {opacity: 1}  
}  
@keyframes fade {  
    from {opacity: .4}  
    to {opacity: 1}  
}  
.text-container {  
\t z-index: 300;  
\t max-width: 80%;  
\t float: center;  
\t text-align: left;  
\t position: relative;  
\t margin-right: auto;  
\t margin-left: auto;  
\t padding-bottom: 2%;  
\t font-family:"GT Walsheim", Calibri, sans-serif;  
}  
.project-description {  
\t width: 100%;  
\t font-size: 36px;  
\t margin-left: 20px;  
\t font-family:"GT Walsheim", Calibri, sans-serif;  
\t display: inline;  
}  
.project-title {  
\t width: 100%;  
\t display: inline;  
\t margin-left: 150px;  
\t text-decoration: underline;  
\t font-size: 36px;  
}

<div class="slideshow-container">  
    <a class="prev" ></a>  
    <a class="next"></a>  
    <div class="mySlides fade">  
    <img src="/wp-content/uploads/new2022/20220327voicc/185154040.jpg" style="width:100%">  
    </div>  
    <div class="mySlides fade">  
    <img src="/wp-content/uploads/new2022/20220327voicc/186154041.jpg" style="width:100%">  
    </div>  
    <div class="mySlides fade">  
    <img src="/wp-content/uploads/new2022/20220327voicc/187154041.jpg" style="width:100%">  
    </div>  
    <div class="mySlides fade">  
    <img src="http://placehold.it/1000x350" style="width:100%">  
    </div>  
<div style="text-align:center">  
    <span class="dot"></span>  
    <span class="dot"></span>  
    <span class="dot"></span>  
    <span class="dot"></span>  
</div>  
</div>  
<div class="text-container">  
\t <div class="project-title">Rust Belt Riders</div>  
\t <div class="project-description">Identity for Rust Belt Riders, a waste management and composting company from Cleveland. </div>  
    </div>  
<br>  
<div class="slideshow-container">  
    <a class="prev" ></a>  
    <a class="next"></a>  
    <div class="mySlides fade">  
    <img src="/wp-content/uploads/new2022/20220327voicc/185154040.jpg" style="width:100%">  
    </div>  
    <div class="mySlides fade">  
    <img src="/wp-content/uploads/new2022/20220327voicc/186154041.jpg" style="width:100%">  
    </div>  
    <div class="mySlides fade">  
    <img src="/wp-content/uploads/new2022/20220327voicc/187154041.jpg" style="width:100%">  
    </div>  
    <div class="mySlides fade">  
    <img src="http://placehold.it/1000x350" style="width:100%">  
    </div>  
<div style="text-align:center">  
    <span class="dot"></span>  
    <span class="dot"></span>  
    <span class="dot"></span>  
</div>  
</div>  
<div class="text-container">  
\t <div class="project-title">Rust Belt Riders</div>  
\t <div class="project-description">Identity for Rust Belt Riders, a waste management and composting company from Cleveland. </div>  
    </div>  
<br>

回答：

这个工作对我来说：（你可能已经忘记了在第二滑点）。看看这个小提琴：https://jsfiddle.net/prtuxoxx/

<div class="slideshow-container"> 
     <a class="prev" ></a> 
     <a class="next"></a> 
     <div class="mySlides fade"> 
      <img src="/wp-content/uploads/new2022/20220327voicc/185154040.jpg" style="width:100%"> 
     </div> 
     <div class="mySlides fade"> 
      <img src="/wp-content/uploads/new2022/20220327voicc/186154041.jpg" style="width:100%"> 
     </div> 
     <div class="mySlides fade"> 
      <img src="/wp-content/uploads/new2022/20220327voicc/187154041.jpg" style="width:100%"> 
     </div> 
     <div class="mySlides fade"> 
      <img src="http://placehold.it/1000x350" style="width:100%"> 
     </div> 
     <div style="text-align:center"> 
     <span class="dot"></span> 
     <span class="dot"></span> 
     <span class="dot"></span> 
     <span class="dot"></span> 
     </div> 
    </div> 
    <div class="text-container"> 
     <div class="project-title">Rust Belt Riders</div> 
     <div class="project-description">Identity for Rust Belt Riders, a waste management and composting company from Cleveland. </div> 
    </div> 
     <br> 
    <div class="slideshow-container"> 
     <a class="prev" ></a> 
     <a class="next"></a> 
     <div class="mySlides fade"> 
      <img src="/wp-content/uploads/new2022/20220327voicc/185154040.jpg" style="width:100%"> 
     </div> 
     <div class="mySlides fade"> 
      <img src="/wp-content/uploads/new2022/20220327voicc/186154041.jpg" style="width:100%"> 
     </div> 
     <div class="mySlides fade"> 
      <img src="/wp-content/uploads/new2022/20220327voicc/187154041.jpg" style="width:100%"> 
     </div> 
     <div class="mySlides fade"> 
      <img src="http://placehold.it/1000x350" style="width:100%"> 
     </div> 
     <div style="text-align:center"> 
     <span class="dot"></span> 
     <span class="dot"></span> 
     <span class="dot"></span> 
     <span class="dot"></span> 
     </div> 
    </div> 
    <div class="text-container"> 
     <div class="project-title">Rust Belt Riders</div> 
     <div class="project-description">Identity for Rust Belt Riders, a waste management and composting company from Cleveland. </div> 
    </div>

和JS：

(function() { 
     init(); //on page load - show first slide, hidethe rest 
     function init() { 
     parents = document.getElementsByClassName('slideshow-container'); 
     for (j = 0; j < parents.length; j++) { 
      var slides = parents[j].getElementsByClassName("mySlides"); 
      var dots = parents[j].getElementsByClassName("dot"); 
      slides[0].classList.add('active-slide'); 
      dots[0].classList.add('active'); 
     } 
     } 
     dots = document.getElementsByClassName('dot'); //dots functionality 
     for (i = 0; i < dots.length; i++) { 
     dots[i].onclick = function() { 
      slides = this.parentNode.parentNode.getElementsByClassName("mySlides"); 
      for (j = 0; j < this.parentNode.children.length; j++) { 
      this.parentNode.children[j].classList.remove('active'); 
      slides[j].classList.remove('active-slide'); 
      if (this.parentNode.children[j] == this) { 
       index = j; 
      } 
      } 
      this.classList.add('active'); 
      slides[index].classList.add('active-slide'); 
     } 
     } 
    //prev/next functionality 
     links = document.querySelectorAll('.slideshow-container a'); 
     for (i = 0; i < links.length; i++) { 
     links[i].onclick = function() { 
      current = this.parentNode; 
      var slides = current.getElementsByClassName("mySlides"); 
      var dots = current.getElementsByClassName("dot"); 
      curr_slide = current.getElementsByClassName('active-slide')[0]; 
      curr_dot = current.getElementsByClassName('active')[0]; 
      curr_slide.classList.remove('active-slide'); 
      curr_dot.classList.remove('active'); 
      if (this.className == 'next') { 
      console.log('next ', curr_slide); 
      if (curr_slide.nextElementSibling.classList.contains('mySlides')) { 
       curr_slide.nextElementSibling.classList.add('active-slide'); 
       curr_dot.nextElementSibling.classList.add('active'); 
      } else { 
       slides[0].classList.add('active-slide'); 
       dots[0].classList.add('active'); 
      } 
      } 
      if (this.className == 'prev') { 
      console.log('previous ', curr_slide); 
       if (curr_slide.previousElementSibling.classList.contains('mySlides')) { 
        curr_slide.previousElementSibling.classList.add('active-slide'); 
        curr_dot.previousElementSibling.classList.add('active'); 
       } else { 
        slides[slides.length - 1].classList.add('active-slide'); 
       dots[slides.length - 1].classList.add('active'); 
      } 
      } 
     } 
     } 
    })();

以上是 上一个按钮导致幻灯片消失 的全部内容， 来源链接： utcz.com/qa/257965.html

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