before-upload不生效

<el-upload 
    drag 
    action 
    multiple
    :file-list="fileList" 
    :on-remove="handleRemove" 
    :auto-upload="false" 
    :on-change="handleChange" 
    :beforeUpload="beforeAvatarUpload">
       <i class="el-icon-upload"></i>
       <div class="el-upload__text">
        将文件拖到此处，或
        <em>点击上传</em>
       </div>
       <div class="el-upload__text">只能上传 xlsx 格式的文件</div>
</el-upload>

因为配置了auto-upload为false，所以beforeUpload没有执行

可以用on-change来进行校验