CSS幻灯片在单击之前不显示图像

我已经通过了您提供的代码和链接。 HTML部分在javascript部分之后加载。 showSlides(slideIndex);
设置的显示属性 slideIndex (即1)阻止 稍后加载HTML部分,它具有 mySlides 对于属性 class 这设置了 display 属性到 none 之后,javascript部分运行得很平稳。 因此,有两种解决方案:

1. 将标记放置在正文标记结束之前。或

2. 援引 showSlides(slideIndex) 加载HTML部分后,将以下代码保留在正文标记的末尾之前:

   <script> showSlides(slideIndex); </script>

I have one sample code ( bootstrap slider )`

 - **enter code here**

`<!DOCTYPE html>
<html lang="en">
<head>
  <title>Bootstrap Example</title>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
</head>
<body>

<div class="container">
  <h2>Carousel Example</h2>  
  <div id="myCarousel" class="carousel slide" data-ride="carousel">
    <!-- Indicators -->
    <ol class="carousel-indicators">
      <li data-target="#myCarousel" data-slide-to="0" class="active"></li>
      <li data-target="#myCarousel" data-slide-to="1"></li>
      <li data-target="#myCarousel" data-slide-to="2"></li>
    </ol>

    <!-- Wrapper for slides -->
    <div class="carousel-inner">
      <div class="item active">
        <img src="la.jpg" alt="Los Angeles" styleenter code here="width:100%;">
      </div>

      <div class="item">
        <img src="chicago.jpg" alt="Chicago" style="width:100%;">
      </div>

      <div class="item">
        <img src="ny.jpg" alt="New york" style="width:100%;">
      </div>
    </div>

    <!-- Left and right controls -->
    <a class="left carousel-control" href="#myCarousel" data-slide="prev">
      <span class="glyphicon glyphicon-chevron-left"></span>
      <span class="sr-only">Previous</span>
    </a>
    <a class="right carousel-control" href="#myCarousel" data-slide="next">
      <span class="glyphicon glyphicon-chevron-right"></span>
      <span class="sr-only">Next</span>
    </a>
  </div>
</div>

</body>
</html>

代码按预期工作,放入一个html文件,该文件按预期工作

<style>
.dealshead section {
    padding-left: 200px;
    float: right;
    position: relative;
    padding-top: 0;
    margin-top: 0;
}

* {
    box-sizing: border-box
}


/* Slideshow container */

.slideshow-container {
    max-height: 300px;
    max-width: 300px;
    margin-top: 0;
}

.mySlides {
    display: none;
}


/* Next & previous buttons */

.prev,
.next {
    cursor: pointer;
    position: absolute;
    top: 50%;
    width: auto;
    margin-top: -45px;
    padding: 16px;
    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 a black background color with a little bit see-through */

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


/* The dots/bullets/indicators */

.dot {
    cursor: pointer;
    height: 15px;
    width: 15px;
    margin: 0 2px;
    background-color: #bbb;
    border-radius: 50%;
    display: inline-block;
    transition: background-color 0.6s ease;
}

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


/* 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
    }
}
</style>


<section>
<img class="mySlides fade" src="images\whiteonblack.jpg" style="width:100%">
<img class="mySlides fade" src="images\blackonwhite.jpg" style="width:100%">
<img class="mySlides fade" src="images\yellowonred.jpg" style="width:100%">
<a class="prev" onclick="plusSlides(-1)">&#10094;</a>
<a class="next" onclick="plusSlides(1)">&#10095;</a>
<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>
</section>

<script>
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";
}
</script>