幻灯片画廊制作成自动画廊

   var slideIndex = 1;
    showSlides(slideIndex);
    
    // Next/previous controls
    function plusSlides(n) {
      showSlides(slideIndex += n);
    }
    
    // Thumbnail image controls
    function currentSlide(n) {
      showSlides(slideIndex = n);
    }
    
    function showSlides(n) {
      var i;
      var slides = document.getElementsByClassName("mySlides");
      var dots = document.getElementsByClassName("demo");
      var captionText = document.getElementById("caption");
      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";
      captionText.innerHTML = dots[slideIndex-1].alt;
    }

* {
      box-sizing: border-box;
    }
    
    /* Position the image container (needed to position the left and right arrows) */
    .container {
      position: relative;
    }
    
    /* Hide the images by default */
    .mySlides {
      display: none;
    }
    
    /* Add a pointer when hovering over the thumbnail images */
    .cursor {
      cursor: pointer;
    }
    
    /* Next & previous buttons */
    .prev,
    .next {
      cursor: pointer;
      position: absolute;
      top: 40%;
      width: auto;
      padding: 16px;
      margin-top: -50px;
      color: white;
      font-weight: bold;
      font-size: 20px;
      border-radius: 0 3px 3px 0;
      user-select: none;
      -webkit-user-select: none;
    }
    
    /* Position the "next button" to the right */
    .next {
      right: 0;
      border-radius: 3px 0 0 3px;
    }
    
    /* On hover, add a black background color with a little bit see-through */
    .prev:hover,
    .next:hover {
      background-color: rgba(0, 0, 0, 0.8);
    }
    
    /* Number text (1/3 etc) */
    .numbertext {
      color: #f2f2f2;
      font-size: 12px;
      padding: 8px 12px;
      position: absolute;
      top: 0;
    }
    
    /* Container for image text */
    .caption-container {
      text-align: center;
      background-color: #222;
      padding: 2px 16px;
      color: white;
    }
    
    .row:after {
      content: "";
      display: table;
      clear: both;
    }
    
    /* Six columns side by side */
    .column {
      float: left;
      width: 16.66%;
    }
    
    /* Add a transparency effect for thumnbail images */
    .demo {
      opacity: 0.6;
    }
    
    .active,
    .demo:hover {
      opacity: 1;
    }

 <!-- Container for the image gallery -->
    <div class="container">
    
      <!-- Full-width images with number text -->
      <div class="mySlides">
        <div class="numbertext">1 / 6</div>
          <img src="img_woods_wide.jpg" style="width:100%">
      </div>
    
      <div class="mySlides">
        <div class="numbertext">2 / 6</div>
          <img src="img_fjords_wide.jpg" style="width:100%">
      </div>
    
      <div class="mySlides">
        <div class="numbertext">3 / 6</div>
          <img src="img_mountains_wide.jpg" style="width:100%">
      </div>
    
      <div class="mySlides">
        <div class="numbertext">4 / 6</div>
          <img src="img_lights_wide.jpg" style="width:100%">
      </div>
    
      <div class="mySlides">
        <div class="numbertext">5 / 6</div>
          <img src="img_nature_wide.jpg" style="width:100%">
      </div>
    
      <div class="mySlides">
        <div class="numbertext">6 / 6</div>
          <img src="img_snow_wide.jpg" style="width:100%">
      </div>
    
      <!-- Next and previous buttons -->
      <a class="prev" onclick="plusSlides(-1)">&#10094;</a>
      <a class="next" onclick="plusSlides(1)">&#10095;</a>
    
      <!-- Image text -->
      <div class="caption-container">
        <p id="caption"></p>
      </div>
    
      <!-- Thumbnail images -->
      <div class="row">
        <div class="column">
          <img class="demo cursor" src="img_woods.jpg" style="width:100%" onclick="currentSlide(1)" alt="The Woods">
        </div>
        <div class="column"> 
          <img class="demo cursor" src="img_fjords.jpg" style="width:100%" onclick="currentSlide(2)" alt="Trolltunga, Norway">
        </div>
        <div class="column">
          <img class="demo cursor" src="img_mountains.jpg" style="width:100%" onclick="currentSlide(3)" alt="Mountains and fjords">
        </div>
        <div class="column">
          <img class="demo cursor" src="img_lights.jpg" style="width:100%" onclick="currentSlide(4)" alt="Northern Lights">
        </div>
        <div class="column">
          <img class="demo cursor" src="img_nature.jpg" style="width:100%" onclick="currentSlide(5)" alt="Nature and sunrise">
        </div> 
        <div class="column">
          <img class="demo cursor" src="img_snow.jpg" style="width:100%" onclick="currentSlide(6)" alt="Snowy Mountains">
        </div>
      </div>
    </div>