滚动图增删另外一个类名

Question

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>

```

Answer 1

<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：