如何修复幻灯片以使点自动运行

Posted 2021-04-12

我尝试显示自动幻灯片。图片正在变化，但下面的点不起作用。当我点击任何一个点时，它都有效，但是我希望每个点在幻灯片更改的同时变为白色。

这是html文件：

<div class="slideshow-container">
            <div class="mySlides fade">
                <img src="images/laptop.png" class="welcome__img" style="width:100%">
            </div>
            <div class="mySlides fade">
                <img src="images/laptop.png" class="welcome__img" style="width:100%">
            </div>
            <div class="mySlides fade">
                <img src="images/laptop.png" class="welcome__img" style="width:100%">
            </div>
            <div style="text-align:center">
                <span class="dot" onclick="currentSlide(1)"></span>
                <span class="dot" onclick="currentSlide(2)"></span>
                <span class="dot" onclick="currentSlide(3)"></span>
            </div>
        </div>

这是css：

.slideshow-container {
  max-width: 1000px;
  position: relative;
  margin: auto;
}

/* Hide the images by default */
.mySlides {
    display: none;
}

.dot {
  cursor: pointer;
  height: 10px;
  width: 10px;
  margin: 0 2px;
  background-color: $grey;
  border-radius: 50%;
  display: inline-block;
  transition: background-color 0.6s ease;
}

.active, .dot:hover {
  background-color: $white;
}

/* Fading animation */
.fade {
  -webkit-animation-name: fade;
  -webkit-animation-duration: 1.5s;
  animation-name: fade;
  animation-duration: 1.5s;
}

@-webkit-keyframes fade {
  from {opacity: .4} 
  to {opacity: 1}
}

@keyframes fade {
  from {opacity: .4} 
  to {opacity: 1}
}

和JS：

var slideIndex = 0;
showSlides();

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


   for (i = 0; i < dots.length; i++) {
      dots[i].className = dots[i].className.replace(" active", "");
  }
    setTimeout(showSlides, 2000); // Change image every 2 seconds
}

setTimeout正常工作，但点不会改变其填充颜色。

答案

把它放在showSlides（）的for循环中。

if (i === slideIndex) {
  dots[i].className = "dot active";
} else {
  dots[i].className = "dot";
}

另一答案

为了在每个幻灯片放映时切换活动类，您可以遍历点：

var dotActive = document.querySelector('.dot.active');
if (dotActive == null) { // if no dot active...
    document.querySelector('.dot').classList.add("active");
} else { // remove current active and set it to next ele
    dotActive.classList.remove("active");
    (dotActive.nextElementSibling || document.querySelector('.dot')).classList.add("active");
}

而不是使用参数（参见1,2,3），您可以使用此参数和事件。

var slideIndex = 0;

showSlides();

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


    var dotActive = document.querySelector('.dot.active');
    if (dotActive == null) {
        document.querySelector('.dot').classList.add("active");
    } else {
        dotActive.classList.remove("active");
        (dotActive.nextElementSibling || document.querySelector('.dot')).classList.add("active");
    }
    setTimeout(showSlides, 2000); // Change image every 2 seconds
}

/* Hide the images by default */
.mySlides {
    display: none;
}
.dot {
    cursor: pointer;
    height: 10px;
    width: 10px;
    margin: 0 2px;
    background-color: grey;
    border-radius: 50%;
    display: inline-block;
    transition: background-color 0.6s ease;
}

.active, .dot:hover {
    background-color: white;
}

/* Fading animation */
.fade {
    -webkit-animation-name: fade;
    -webkit-animation-duration: 1.5s;
    animation-name: fade;
    animation-duration: 1.5s;
}

@-webkit-keyframes fade {
    from {opacity: .4}
    to {opacity: 1}
}

@keyframes fade {
    from {opacity: .4}
    to {opacity: 1}
}

<div class="slideshow-container">
    <div class="mySlides fade">
        <img src="https://dummyimage.com/100x100/000/fff&text=1" class="welcome__img" style="width:100%">
    </div>
    <div class="mySlides fade">
        <img src="https://dummyimage.com/100x100/000/fff&text=2" class="welcome__img" style="width:100%">
    </div>
    <div class="mySlides fade">
        <img src="https://dummyimage.com/100x100/000/fff&text=3" class="welcome__img" style="width:100%">
    </div>
    <div style="text-align:center">
        <span class="dot" onclick="currentSlide(1)"></span>
        <span class="dot" onclick="currentSlide(2)"></span>
        <span class="dot" onclick="currentSlide(3)"></span>
    </div>
</div>

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