vue upload 上传多个文件只发一次请求

代码

<div id="app">
  <el-upload 
    :headers="headers" 
    v-loading="uploadLoading" 
    :before-upload="beforeUpload" 
    ref="upload" 
    :action="action"
    accept=".pdf,.doc,.docx,.png,.jpg" drag multiple 
    :limit="3" class="upload" 
    :on-remove="handleRemove"
    :file-list="fileList" 
    :auto-upload="false" 
    :on-change="updateChange" 
    :before-remove="beforeRemove">
  </el-upload>
</div>