vue实现鼠标移入小图片，大图显示效果

第一步，先设置ref，和移入事件

 <div class="story-container" ref="storyContainer">
                                        <div class="item-box" v-for="(item,index) in testImg" :key="index" @mouseover="showPic(index)">
                                            <a class="item-a"  :href="item.img">
                                                <img  :src="item.img" alt="">
                                            </a>
                                        </div>
                                    </div>

右边大图片

v-for里面的 testImg

 testImg:[
                {img:'https://img2.baidu.com/it/u=631618391,2322805080&fm=253&fmt=auto&app=138&f=JPEG?w=500&h=500'},
                {img:'https://img1.baidu.com/it/u=3393614753,2638302835&fm=253&fmt=auto&app=138&f=JPEG?w=500&h=500'},
                {img:'https://img2.baidu.com/it/u=631618391,2322805080&fm=253&fmt=auto&app=138&f=JPEG?w=500&h=500'},
                {img:'https://img1.baidu.com/it/u=3393614753,2638302835&fm=253&fmt=auto&app=138&f=JPEG?w=500&h=500'},
                {img:'https://img2.baidu.com/it/u=631618391,2322805080&fm=253&fmt=auto&app=138&f=JPEG?w=500&h=500'},
                {img:'https://img1.baidu.com/it/u=3393614753,2638302835&fm=253&fmt=auto&app=138&f=JPEG?w=500&h=500'},
                {img:'https://img1.baidu.com/it/u=3393614753,2638302835&fm=253&fmt=auto&app=138&f=JPEG?w=500&h=500'},
            ],

第二步，实现的方法

  // 鼠标放上小图片,大图片显示
        showPic(whiPic){
            let linksA=this.sCont.getElementsByClassName('item-a');
            let sourceA=linksA[whiPic].getAttribute('href');
            for(let i=0;i<linksA.length;i++){
               linksA[i].classList.remove('hover');
            }
            linksA[whiPic].classList.add('hover');
            this.showImgBig.setAttribute('src',sourceA)
        },

第三步，获取ref,在什么周期的mounted()里面

这里的this.sCont，，这个sCont是要写在data(){return{ sCont:'' , }} 里面定义的，包括showImgBig

 mounted() {

if(!this.$refs.storyContainer) return false;if(!this.$refs.showImgBig) return false;
        this.sCont=this.$refs.storyContainer;
  this.showImgBig=this.$refs.showImgBig;
        // console.log(this.sCont)
        // console.log(this.hScroll)
        // console.log(this.btnScrollLeft)
        // console.log( this.btnScrollRight)
        // console.log(this.maxScroll)
    },