使用FileReader对象读取文件内容，最后将文件内容进行处理使用

<template>
  <a-upload :accept="acceptType.toString()" :showUploadList="false" :before-upload="beforeUpload" :customRequest="customUpload">
        <i class="iconfont icon-daoru icon-size icon-hover"></i>
      </a-upload>
</template>

<script>
const acceptType = ['application/json'];
  const dataFn: any = ref();
  const beforeUpload = (file) => {
    dataFn.value = () => {
      return new Promise((resolve, reject) => {
        console.log(file);
        if (acceptType.find((type) => type === file.type)) {
          resolve(true);
        } else {
          message.warn('请上传正确格式文件');
          reject(false);
        }
      }).finally(() => {});
    };
  };
  // 自定义上传
  const customUpload = (data) => {
    dataFn
      .value()
      .then((res) => {
        console.log(data, res);
        if (res) {
          const reader = new FileReader();
          console.log(reader);
          reader.onload = (e) => {
            const fileContent = e.target.result;
            console.log(fileContent, JSON.parse(fileContent));
          };
          reader.readAsText(data.file);
        }
      })
      .catch((_err) => {});
  };
</script>

reader.readAsText(data.file)中data.file的数据格式为