Javascript - CSS 幻灯片不显示默认图像

Question

我在当前的 passion-project 中实现的 CSS 幻灯片放映有问题，其中在加载网页时没有显示默认图像。导航/点按后，图像成功显示，但我似乎无法弄清楚将在页面加载时显示第一张图像的小代码片段(可能是 Javascript 函数中缺少的)。我试图简单地将“事件”类添加到所需的图像，但这只会使“点”按钮显示为事件状态，而不会显示相应的图像。感谢任何帮助

代码如下:

var slideIndex = 1;



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

function currentSlide(n) {
  'use strict';
  showSlides(slideIndex = n);
}

function showSlides(n) {
  'use strict';
  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";
}

* {
  box-sizing: border-box
}

body {
  font-family: Verdana, sans-serif;
  margin: 0
}

.mySlides {
  display: none
}


/* Slideshow container */

.slideshow-container {
  max-width: 400px;
  position: relative;
  margin: auto;
}


/* Next & previous buttons */

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


/* Position the "next button" to the right */

.next {
  right: 0;
  border-radius: 3px 0 0 3px;
}


/* On hover, add see-through background */

.prev:hover,
.next:hover {
  background-color: rgba(0, 0, 0, 0.8);
}


/* Caption text */

.text {
  color: #f2f2f2;
  font-size: 15px;
  padding: 8px 12px;
  position: absolute;
  bottom: 8px;
  width: 100%;
  text-align: center;
}


/* Number text (1/3 etc) */

.numbertext {
  color: #f2f2f2;
  font-size: 12px;
  padding: 8px 12px;
  position: absolute;
  top: 0;
}


/*  */

.transition {
  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,
.transition:hover {
  background-color: #222;
}


/* 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
  }
}


/* On smaller screens, decrease text size */

@media only screen and (max-width: 300px) {
  .prev,
  .next,
  .text {
    font-size: 11px
  }
}

<div class="homePage">
  <div class="slideshow-container">

    <div class="mySlides fade">
      <div class="numbertext">1 / 2</div>
      <img src="graphics/logo.jpg" style="width:100%">
      <div class="text"></div>
    </div>

    <div class="mySlides fade">
      <div class="numbertext">2 / 2</div>

      <img src="graphics/1.jpg" style="width:100%">
      <div class="text"></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="transition" onclick="currentSlide(1)"></span>
    <span class="transition" onclick="currentSlide(2)"></span>

    <br>
  </div>

Answer 1

您可以为 slider 中的第一张图片指定另一个类

<div class="mySlides fade block ">
 <div class="numbertext">1 / 2</div>
  <img src="#" style="width:100%">
  <div class="text"></div>
</div>

然后你给它一个display:block

.block {
 display:block;
}

示例:https://jsfiddle.net/1ueun1L1/2/