滚动图增删另外一个类名
问题描述：
根据swiper滚动图来改变另外一个head类名.
在切换到class=“turn”这张图的时候，刚好选中是swiper-slide-active就在class=“head”上增加on
swiper-slide-active离开class=“turn”的时候，就head的on消失
版本：Swiper 4.5.0
选中状态：swiper-slide-active
```html
<div class="head"></div>
<div class="swiper-container">
<div class="swiper-wrapper">
<div class="swiper-slide turn swiper-slide-active"></div>
<div class="swiper-slide"></div>
<div class="swiper-slide"></div>
</div>
</div>
```
答
<link href="https://cdn.bootcdn.net/ajax/libs/Swiper/4.5.0/css/swiper.min.css" rel="stylesheet">
<div class="head"></div>
<div class="swiper-container">
<div class="swiper-wrapper">
<div class="swiper-slide turn ">1</div>
<div class="swiper-slide">2</div>
<div class="swiper-slide">3</div>
</div>
</div>
<script src="https://cdn.bootcdn.net/ajax/libs/Swiper/4.5.0/js/swiper.min.js"></script>
<script>
var mySwiper = new Swiper('.swiper-container',{
autoplay: {
delay:2500,
disableOnInteraction: false,
},
on:{
slideChange: function(){
var x = document.querySelectorAll(".swiper-slide");
var result = x[this.activeIndex].getAttribute('class');
console.log(this.activeIndex)
console.log(result)
if(result.indexOf('turn') > -1){//this.activeIndex表示当前展示的下标，所以只要滚动到当前元素含有 turn即可
document.querySelector('.head').classList.add("select");
}
else{
document.querySelector('.head').classList.remove("select");
}
},
},
})
</script>
结果如下：
答
应该有 图片 切换 的事件 。你在里面 判断 一下 是不是 class 为 turn然后 js改变 类名