element ui 中 el-button重新渲染后disabled属性失效

调试发现:disabled绑定的值和显示没有保持一致，发现是disabled属性失效

解决方式：

给标签添加key
比如：key=“isOldVersion”

 <el-form-item>
    <el-button type="primary" style="margin-left: 100px;" @click="snoreDialogVisible=false">返回</el-button>
    <el-button v-if="isNewVersion==false" key="isOldVersion" type="danger" style="margin-left: 100px;" @click="endSnoreParams">设置</el-button>
    <el-button v-if="isNewVersion" key="isNewVersion" type="danger" style="margin-left: 100px;" :disabled="selectBedSide===''" @click="endSnoreParams">设置</el-button>
  </el-form-item>