vue调用组件遇到的坑

今天再用element-ui的el-tab调用不同的组件时遇到一个奇怪的问题，

上述图片中，一个组件被重复渲染了多次，代码如下：

<el-tabs ref="tabRef" v-model="activeName" @tab-click="handleClick">
      <el-tab-pane
        v-for="item in options.tabs"
        :key="item.name"
        :label="item.label"
        :name="item.name"
      >
        <!-- <keep-alive>
          <div :is="item.name"></div>
        </keep-alive> -->

        <QualificationDetail v-if="activeName == 'QualificationDetail'" :isEdit="item.isEdit" />
        <WarehousingDetail v-if="activeName == 'WarehousingDetail'" />
        <AuditProcess v-if="activeName == 'AuditProcess'" />
        <SampleRegist v-if="activeName == 'SampleRegist'"></SampleRegist>
        <SampleRegistDetail v-if="activeName == 'SampleRegistDetail'"></SampleRegistDetail>
        <InspectRegist v-if="activeName == 'InspectRegist'" v-on="$listeners"></InspectRegist>
        <InspectRegistDetail v-if="activeName == 'InspectRegistDetail'"></InspectRegistDetail>
        <InspectReview v-if="activeName == 'InspectReview'" :isEdit="item.isEdit"></InspectReview>
      </el-tab-pane>
    </el-tabs>

虽然上述代码没有问题，没有报错，但是这样明显是不对的，查询了下，然后做了改正：

<el-tabs ref="tabRef" v-model="activeName" @tab-click="handleClick">
      <el-tab-pane
        v-for="item in options.tabs"
        :key="item.name"
        :label="item.label"
        :name="item.name"
      >
        <keep-alive>
          <div :is="item.name"></div>
        </keep-alive>
      </el-tab-pane>
    </el-tabs>

这样DOM树渲染就正常了，

原因是：使用v-if会本身就会造成多次渲染

看了下官网解释的很好，给出的例子也很好：https://cn.vuejs.org/v2/guide/components-dynamic-async.html