js首页轮播
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问题描述：实现如下图的轮播效果。
解决办法：
<style type="text/css">
/*标题样式*/
.app {
width: 100%;
text-align: center;
}
.app .scroll {
position: relative;
display: inline-block;
height: 460px;
width: 100%;
}
.app .scroll .img {
display: none;
width: 100%;
height: 460px;
}
.app .scroll .current {
display: block;
}
.app .scroll .lf {
position: absolute;
top: 50%;
left: 10px;
background-image: url('images/arrow.png');
background-position: -83px 0;
width: 41px;
height: 69px;
cursor: pointer;
transform: translateY(-50%);
}
.app .scroll .lr {
position: absolute;
top: 50%;
right: 10px;
background-image: url('images/arrow.png');
background-position: -123px 0;
width: 41px;
height: 69px;
cursor: pointer;
transform: translateY(-50%);
}
.app .dots {
margin-top: -33px;
z-index: 999;
position: relative;
}
.app .dots>span {
display: inline-block;
box-sizing: border-box;
width: 11px;
height: 11px;
border: 3px solid red;
border-radius: 15px;
cursor: pointer;
}
.app .dots>span:not(:last-child) {
margin-right: 5px;
}
/* 小圆点的颜色 */
.app .dots .square {
background: #f46;
}
</style>
<div class="container-fluid">
<div class="app">
<div class="scroll">
<!-- 图片展示 -->
<img src="images/banner1.jpg" alt="scrollImage" class="img current">
<img src="images/banner1.jpg" alt="scrollImage" class="img">
<img src="images/banner.jpg" alt="scrollImage" class="img">
<img src="images/banner1.jpg" alt="scrollImage" class="img">
<img src="images/banner.jpg" alt="scrollImage" class="img">
<!-- 左右箭头的展示 -->
<div class="lf"></div>
<div class="lr"></div>
<!-- 小圆点展示 -->
<div class="dots">
<span class="square"></span>
<span></span>
<span></span>
<span></span>
<span></span>
</div>
</div>
</div>
</div>
<script type="text/javascript">
window.addEventListener('load', function() {
var leftArrow = this.document.querySelector('.lf');
var rightArrow = this.document.querySelector('.lr');
// 鼠标移动到左右箭头的位置更换图片 有灰色背景的图片
leftArrow.addEventListener('mouseenter', function() {
this.style.backgroundPosition = '0 0';
});
leftArrow.addEventListener('mouseleave', function() {
this.style.backgroundPosition = '-83px 0';
});
rightArrow.addEventListener('mouseenter', function() {
this.style.backgroundPosition = '-42px 0';
});
rightArrow.addEventListener('mouseleave', function() {
this.style.backgroundPosition = '-123px 0';
});
// 获取图片 和 小点
var imgs = this.document.querySelectorAll('.img');
var dots = this.document.querySelector('.dots').querySelectorAll('span');
// 给图片设置index 属性，好判断当前的图片是哪一张
for (let i = 0; i < imgs.length; i++) {
imgs[i].setAttribute('data-index', i);
}
// 获取当前图片 和 图片的index（数组下标）
var current = this.document.querySelector('.current');
var currentIndex = current.getAttribute('data-index');
// 左箭头的点击事件，点击了就返回前一张图片
// 如果当前图片为第一张那么需要更换到最后一张图片也就是第四张
leftArrow.addEventListener('click', function() {
if (currentIndex > 0) {
imgs[currentIndex].classList.remove('current');
dots[currentIndex].classList.remove('square');
imgs[--currentIndex].classList.add('current');
dots[currentIndex].classList.add('square');
} else {
imgs[currentIndex].classList.remove('current');
dots[currentIndex].classList.remove('square');
currentIndex = 4;
imgs[currentIndex].classList.add('current');
dots[currentIndex].classList.add('square');
}
});
// 点击右箭头下一张图片切换
// 如果当前为第五张图片，那么切换回第一张图片
rightArrow.addEventListener('click', changeImage);
var timer = this.setInterval(changeImage, 8000);
function changeImage() {
if (currentIndex < 4) {
imgs[currentIndex].classList.remove('current');
dots[currentIndex].classList.remove('square');
imgs[++currentIndex].classList.add('current');
dots[currentIndex].classList.add('square');
} else {
imgs[currentIndex].classList.remove('current');
dots[currentIndex].classList.remove('square');
currentIndex = 0;
imgs[currentIndex].classList.add('current');
dots[currentIndex].classList.add('square');
}
};
// 小圆点的点击事件
for (let k = 0; k < dots.length; k++) {
dots[k].setAttribute('data-index', k);
dots[k].addEventListener('click', function() {
var index = this.getAttribute('data-index');
if (index != currentIndex) {
imgs[currentIndex].classList.remove('current');
dots[currentIndex].classList.remove('square');
imgs[index].classList.add('current');
dots[index].classList.add('square');
currentIndex = index;
}
})
}
});
</script>