使用邮递员时，多个未填充req.files

<form action="/upload" method="post" enctype="multipart/form-data">
  <input type="file" name="file1" id="file1">
  <input type="file" name="file2" id="file2">
  <input type="submit" value="Upload">
</form>

<script>
  document.querySelector('form').addEventListener('submit', function(event) {
    var file1 = document.getElementById('file1').files[0];
    var file2 = document.getElementById('file2').files[0];

    if (!file1) {
      event.preventDefault(); // 阻止表单提交
      alert('请先选择文件1');
    }

    if (!file2) {
      event.preventDefault(); // 阻止表单提交
      alert('请先选择文件2');
    }
  });
</script>

const multer = require('multer');

const storage = multer.diskStorage({
  destination: function (req, file, cb) {
    cb(null, 'uploads/');
  },
  filename: function (req, file, cb) {
    cb(null, file.originalname);
  }
});

const fileFilter = function (req, file, cb) {
  if (!file.originalname) {
    // 忽略空文件字段
    cb(null, false);
  } else {
    cb(null, true);
  }
};

const upload = multer({ storage: storage, fileFilter: fileFilter });

app.post('/upload', upload.array('file'), function (req, res) {
  // 处理文件上传
});