vue最简单的移入切换active

 <li :key="index" class="clearfix" :class="timeIndex === index ? 'clearfix hover' : 'clearfix' " @mouseover="selectTimer(index)">

selectTimer(index) {
      this.timeIndex = index
    },

参靠文章：https://blog.csdn.net/yibowanbo/article/details/79703575