javascript - w3.css 幻灯片 : How to add automatic slideshow functionality

Question

我想每 4-5 秒从 w3.css 库将此幻灯片自动转换为幻灯片。也可以在 w3schools editor 找到.

可以找到 w3.css 幻灯片的更多文档 here

我需要以某种方式添加此代码以自动制作图像幻灯片，但保留元素符号背景并使箭头起作用:

var slideIndex = 0;
carousel();
function carousel() {
    var i;
    var x = document.getElementsByClassName("mySlides");
    for (i = 0; i < x.length; i++) {
      x[i].style.display = "none"; 
    }
    slideIndex++;
    if (slideIndex > x.length) {slideIndex = 1} 
    x[slideIndex-1].style.display = "block"; 
    setTimeout(carousel, 2000); // Change image every 2 seconds
}

完整代码如下:

var slideIndex = 1;
showDivs(slideIndex);

function plusDivs(n) {
  showDivs(slideIndex += n);
}

function currentDiv(n) {
  showDivs(slideIndex = n);
}

function showDivs(n) {
  var i;
  var x = document.getElementsByClassName("mySlides");
  var dots = document.getElementsByClassName("demo");
  if (n > x.length) {slideIndex = 1}    
  if (n < 1) {slideIndex = x.length}
  for (i = 0; i < x.length; i++) {
     x[i].style.display = "none";  
  }
  for (i = 0; i < dots.length; i++) {
     dots[i].className = dots[i].className.replace(" w3-white", "");
  }
  x[slideIndex-1].style.display = "block";  
  dots[slideIndex-1].className += " w3-white";
}

.mySlides {display:none}
.w3-left, .w3-right, .w3-badge {cursor:pointer}
.w3-badge {height:13px;width:13px;padding:0}

<link rel="stylesheet" href="https://www.w3schools.com/w3css/4/w3.css">

<div class="w3-container">
  <h2>Slideshow Indicators</h2>
  <p>An example of using buttons to indicate how many slides there are in the slideshow, and which slide the user is currently viewing.</p>
</div>

<div class="w3-content w3-display-container" style="max-width:800px">
  <img class="mySlides" src="https://cdn-s3.si.com/styles/marquee_large_2x/s3/images/trump-5.jpg" style="width:100%">
  <img class="mySlides" src="https://i.ytimg.com/vi/VpevTNRK-_M/maxresdefault.jpg" style="width:100%">
  <img class="mySlides" src="https://img00.deviantart.net/a73e/i/2015/261/4/3/the_magic_world_by_chibionpu-d4ol7wm.jpg" style="width:100%">
  <div class="w3-center w3-container w3-section w3-large w3-text-white w3-display-bottommiddle" style="width:100%">
    <div class="w3-left w3-hover-text-khaki" onclick="plusDivs(-1)">&#10094;</div>
    <div class="w3-right w3-hover-text-khaki" onclick="plusDivs(1)">&#10095;</div>
    <span class="w3-badge demo w3-border w3-transparent w3-hover-white" onclick="currentDiv(1)"></span>
    <span class="w3-badge demo w3-border w3-transparent w3-hover-white" onclick="currentDiv(2)"></span>
    <span class="w3-badge demo w3-border w3-transparent w3-hover-white" onclick="currentDiv(3)"></span>
  </div>
</div>

Answer 1

setInterval(function(){
    slideIndex++;
    currentDiv(slideIndex);
}, 2000);

将此添加到您的 code example最后