我使用 JavaScript、CSS 和 HTML 制作了一个幻灯片。代码跳过了最后一张幻灯片，我不明白为什么。所以，如果有人能启发它为什么这样做，那就太好了。
我尝试过更改 JavaScript 中的内容，例如添加到幻灯片或删除 -1，我知道我需要它，但没有任何效果，我感到很困惑。
window.onload = function() { // add window.onload here and set it euqal to a function
var timeOut;
var slideIndex = 0;
var slides;
showSlides(slideIndex);
// Next/previous controls
window.plusSlides = function(n) {
showSlides(n);
}
// Thumbnail image controls
window.currentSlide = function(n) {
slideIndex = (n - 1)
showSlides();
}
function bind() {
clearInterval(timeOut)
timeOut = setInterval(showSlides, 5000);
}
function showSlides(n) {
var i;
slides = document.getElementsByClassName("mySlides");
var dots = document.getElementsByClassName("dot");
for (i = 0; i < slides.length; i++) {
slides[i].style.display = "none";
}
if (n)
slideIndex += n;
else slideIndex++;
if (slideIndex >= slides.length || slideIndex < 1) {
slideIndex = 1
}
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";
bind();
}
}* {
box-sizing: border-box
}
/* Slideshow container */
.slideshow-container {
max-width: 1000px;
position: relative;
margin: auto;
}
/* Hide the images by default */
.mySlides {
display: none;
}
/* Next & previous buttons */
.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;
user-select: none;
}
/* Position the "next button" to the right */
.next {
right: -15px;
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);
}
*/
/* Caption text */
.text {
color: #f2f2f2;
font-size: 28px;
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;
}
/* 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
}
}<div class="slideshow-container">
<!-- Full-width images with number and caption text -->
<div class="mySlides fade">
<img src="https://upload.wikimedia.org/wikipedia/commons/e/e1/Nuernberg-fronfeste-und-kettensteg-v-O.jpg" style="width:1000px; height: 540px;">
<div class="text"><span style="background-color: black">one on one weekly siminars</span></div>
</div>
<div class="mySlides fade">
<img src="https://upload.wikimedia.org/wikipedia/commons/e/e1/Nuernberg-fronfeste-und-kettensteg-v-O.jpg" style="width:1000px; height: 540px;">
<div class="text"><span style="background-color: black">monthly seminars/workshops</span></div>
</div>
<div class="mySlides fade">
<img src="https://upload.wikimedia.org/wikipedia/commons/e/e1/Nuernberg-fronfeste-und-kettensteg-v-O.jpg" style="width:1000px; height: 540px;">
<div class="text"><span style="background-color: black">nursing home visits</span></div>
</div>
<div class="mySlides fade">
<img src="https://upload.wikimedia.org/wikipedia/commons/e/e1/Nuernberg-fronfeste-und-kettensteg-v-O.jpg" style="width:1000px; height: 540px;">
<div class="text"><span style="background-color: black">community service</span></div>
</div>
<div class="mySlides fade">
<img src="https://upload.wikimedia.org/wikipedia/commons/e/e1/Nuernberg-fronfeste-und-kettensteg-v-O.jpg" style="width:1000px; height: 540px;">
<div class="text"><span style="background-color: black">college visits</span></div>
</div>
<div class="mySlides fade">
<img src="https://upload.wikimedia.org/wikipedia/commons/e/e1/Nuernberg-fronfeste-und-kettensteg-v-O.jpg" style="width:1000px; height: 540px;">
<div class="text"><span style="background-color: black">Annual Summer Retreat</span></div>
</div>
<div class="mySlides fade">
<img src="pictures%20updated/12.jpg" style="width:1000px; height: 540px;">
<div class="text"><span style="background-color: black">Annual Horse Camp</span></div>
</div>
<div class="mySlides fade">
<img src="https://upload.wikimedia.org/wikipedia/commons/e/e1/Nuernberg-fronfeste-und-kettensteg-v-O.jpg" style="width:1000px; height: 540px;">
<div class="text"><span style="background-color: black">Annual Horse Camp</span></div>
</div>
<!-- Next and previous buttons -->
<a class="prev" onclick="plusSlides(-1)">❮</a>
<a class="next" onclick="plusSlides(1)">❯</a>
</div>
<br>
<!-- The dots/circles -->
<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>
<span class="dot" onclick="curretnslide(4)"></span>
<span class="dot" onclick="currentslide(5)"></span>
<span class="dot" onclick="currentslide(6)"></span>
<span class="dot" onclick="currentslide(7)"></span>
<span class="dot" onclick="currentslide(8)"></span>
</div>
</body>最佳答案
您的函数 showSlides() 检查 slideIndex 是否大于或等于 幻灯片的长度。然后使用 slideIndex - 1 访问幻灯片元素。在 slideIndex == slides.length 的情况下，您将重置为 1，即使您在数组括号内考虑了偏移量 1(从 1 开始计数)。
下面更正的 if 语句应该可以工作:
if (slideIndex > slides.length || slideIndex < 1) {
slideIndex = 1
}
我建议您避免在数组括号内执行算术运算。当您这样做时，它破坏了名称“slideIndex”的含义，因为它并不是您正在使用的真正的幻灯片索引。
关于javascript - 为什么幻灯片会跳过最后一张幻灯片？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/54562598/