安装multer

npm i multer

引入依赖

const path = require("path");
const multer = require("multer");

代码示例

前端代码

const newFormData = new FormData();
newFormData.append("file", file);
axios.post("/notez/file/upload", newFormData, {
		headers: {},
}).then((res) => {
	if (res.data.code == 200) {
		 console.log(res.data);
	}
});

后端代码

let storage = multer.diskStorage({
  //设置 上传图片服务器位置
  destination: path.resolve(__dirname, "./public/img"),
  //设置 上传文件保存的文件名
  filename: function (req, file, cb) {
    // 获取后缀扩展
    let extName = path.extname(file.originalname); //.jpg
    // 获取名称
    let fileName = Date.now();

    // console.log(fileName + extName); //12423543465.jpg
    cb(null, fileName + extName);
  },
});
let fileFilter = function (req, file, cb) {
  let acceptableMime = ["image/jpeg", "image/png", "image/jpg", "image/gif"];
  // 限制类型
  // null是固定写法
  if (acceptableMime.indexOf(file.mimetype) !== -1) {
    cb(null, true); // 通过上传
  } else {
    cb(null, false); // 禁止上传
  }
};
let limits = {
  fileSize: "2MB", //设置限制（可选）
};

const imageUploader = multer({ fileFilter, storage, limits }).single("file"); //文件上传预定 name 或者 字段
router.post("/file/upload", imageUploader, (req, res, next) => {
  let username = req.headers["username"];
  let password = req.headers["password"];
  // console.log(req.file);
  if (config.login.username == username && config.login.password == password) {
    try {
      let name = path.basename(req.file.path);
      res.json({
        message: "操作成功！",
        code: 200,
        url: "/img/" + name,
        name,
      });
    } catch (error) {
      console.log(error);
      res.json({ message: "操作失败！", code: 500 });
    }
  } else {
    res.json({ message: "请登录后再试！", code: 400 });
  }
});