用來(lái)解析上傳文件的

  useXMLHttpRequest = (url, formData) => {
    let percent = "Not start";

    let xhr = new XMLHttpRequest();

    xhr.upload.addEventListener("progress", (rs) => {
      if(rs.lengthComputable) {
        percent = (rs.loaded / rs.total * 100).toFixed(2);
        this.setState({status: percent});
      }
    }, false);

    xhr.addEventListener("readystatechange", () => {
      let rs = xhr;
      if(rs.status !== 200) {
        console.log("failed")
      } else if(rs.status === 4) {
        console.log("success")
      }
    });

    xhr.open("post", url, true);
    xhr.send(formData);
  }

router.post('/upload', function(req, res, next) {

  let count = 0;
  console.log("upload")
  res.header("Access-Control-Allow-Origin", "*");


  let options = {
    autoFiles: true,
    uploadDir: "tmp"
  }

  let form = new multiparty.Form(options);

  form.on("close", () => {
    console.log("upload complete");
    res.json({info: "success"});
  })

  form.on("error", (err) => {
    res.json({info: err});
  })

  form.parse(req);

});