解决element-ui upload组件在选择文件前进行弹窗提

<el-button ref="updataButt" @click="clickSubmit">导入</el-button >
                <el-upload
                        class="uploadExcel"
                        ref="upload"
                        accept=".xls, .xlsx"
                        :action="uploadFileURL"
                        :data="uploadParam"
                        name="file"
                        :headers="header"
                        :before-remove="beforeReExcel"
                        :on-success="successExcel"
                        :on-change="changeUpExcel"
                        :on-error="errorExcel"
                        :auto-upload="true"
                        :before-upload="beforeUpExcel"
                        :show-file-list="false"
                >

                </el-upload>

methods: {
//点击先弹窗在上传
    clickSubmit(){
      let self = this;
      //这个地方根据自己的业务续修进行判断和调整
      if(self.uploadParam.kmMc){
        //这个弹窗是我自己根据element 二次封装的一个弹窗
        self.$JcMsgBox(
          "此操作将导入"+self.uploadParam.kmMc+"科目的保密对应关系，是否继续",
          "warning",
          "温馨提示"
        )
          .then(() => {
            //这句话就是弹窗点击确定之后进行弹出选择文件
            //其中的upload对应着ref
            self.$refs['upload'].$refs['upload-inner'].handleClick()
          })
          .catch(() => {
            self.$message({
              type: "info",
              message: "已取消导入"+self.uploadParam.kmMc+"科目的保密对应关系"
            });
          });
      }else{
        self.$message({
          type: "danger",
          message: "请先选择科目"
        });
      }

    }
}