如何实现幻灯片效果/图片轮播

幻灯片效果/图片轮播通常用来循环显示某些元素,常使用在网站与app首页。例如本站首页所使用的图片轮播:

创建幻灯片特效

第一步:添加HTML

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>幻灯片特效/图片轮播演示</title>
<link rel="stylesheet" href="style.css">
</head>

<body>

<div class="slideshow-container">
  <div class="mySlides fade">
    <div class="numbertext">1 / 3</div>
    <img src="img1.jpg" style="width:100%">
    <div class="text">幻灯片1</div>
  </div>

  <div class="mySlides fade">
    <div class="numbertext">2 / 3</div>
    <img src="img2.jpg" style="width:100%">
    <div class="text">幻灯片2</div>
  </div>

  <div class="mySlides fade">
    <div class="numbertext">3 / 3</div>
    <img src="img3.jpg" style="width:100%">
    <div class="text">幻灯片3</div>
  </div>

  <a class="prev" onclick="plusSlides(-1)">&#10094;</a>
  <a class="next" onclick="plusSlides(1)">&#10095;</a>
</div>
<br>

<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>

<!-- js文件最后加载,提高页面呈现速度 -->
<script src="carousel.js"></script>

</body>
</html>

第二步:添加CSS(style.css)

@charset "utf-8";
* {box-sizing:border-box}

/* 幻灯片容器 */
.slideshow-container {
  max-width: 1000px;
  position: relative;
  margin: auto;
}

.mySlides {
    display: none;
}

/* 向前向后按钮 */
.prev, .next {
  cursor: pointer;
  position: absolute;
  top: 50%;
  width: auto;
  margin-top: -22px;
  padding: 16px;
  color: white;
  font-weight: bold;
  font-size: 18px;
  transition: 0.6s ease;
  border-radius: 0 3px 3px 0;
}

/* 向后按钮置于右边 */
.next {
  right: 0;
  border-radius: 3px 0 0 3px;
}

/* 鼠标滑过按钮,添加黑色背景 */
.prev:hover, .next:hover {
  background-color: rgba(0,0,0,0.8);
}

/* 图片说明文字 */
.text {
  color: #f2f2f2;
  font-size: 15px;
  padding: 8px 12px;
  position: absolute;
  bottom: 8px;
  width: 100%;
  text-align: center;
}

/* 数字 (1/3 等) */
.numbertext {
  color: #f2f2f2;
  font-size: 12px;
  padding: 8px 12px;
  position: absolute;
  top: 0;
}

/* 下方指示器 */
.dot {
  cursor:pointer;
  height: 13px;
  width: 13px;
  margin: 0 2px;
  background-color: #bbb;
  border-radius: 50%;
  display: inline-block;
  transition: background-color 0.6s ease;
}

.active, .dot:hover {
  background-color: #717171;
}

/* 渐隐动画 */
.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}
}

第三步:添加js(carousel.js)

var slideIndex = 1;
showSlides(slideIndex);

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

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

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

如果改为自动播放幻灯片,则使用如下js:

var slideIndex = 0;
showSlides();

function showSlides() {
    var i;
    var slides = document.getElementsByClassName("mySlides");
    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"; 
    setTimeout(showSlides, 2000); // Change image every 2 seconds
}