从ExpressJs向React发送文件

npm install multer

const multer = require('multer');

const storage = multer.diskStorage({
  destination: function (req, file, cb) {
    cb(null, 'uploads/'); // 指定文件上传的目标路径
  },
  filename: function (req, file, cb) {
    cb(null, file.originalname); // 指定文件上传后的文件名
  }
});

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

app.post('/upload', upload.single('file'), function (req, res, next) {
  // 文件上传成功后的处理逻辑
});

const fileInput = document.querySelector('input[type="file"]');
const formData = new FormData();

formData.append('file', fileInput.files[0]);

fetch('/upload', {
  method: 'POST',
  body: formData
})
.then(response => response.json())
.then(data => {
  // 文件上传成功后的处理逻辑
})
.catch(error => {
  // 文件上传失败后的处理逻辑
});