Node.js file upload server without third party module

问题

I want to parse the upload file and saved without any 3rd module but still not success. Do I miss any part?

Or it need to convert to buffer first?

var http = require('http');
const fs = require ('fs');

http.createServer(function (req, res) {
  if (req.url == '/fileupload') {
    var body = '';
    req.on('data', (data) => {
      body += data;
    });
    req.on('end', () => {

      body = body.replace(/-.+-/g, '').replace(/WebKit.+|Contentdata.+|Content-Type.+/g, '');
      fs.writeFile('test.png', body, (err) => {
        if (err) throw err;
        console.log('The file has been saved!');
      });
      res.end(body);
    })
  } else {
    res.writeHead(200, { 'Content-Type': 'text/html' });
    res.write('<form action="fileupload" method="post" enctype="multipart/form-data">');
    res.write('<input type="file" name="filetoupload"><br>');
    res.write('<input type="submit">');
    res.write('</form>');
    return res.end();
  }
}).listen(8080);

回答1:

Ref:Form submission

req.on('data', (data) => {
  body += data;
});

First, the data is a Buffer. You cannot use the + operator directly. And also because of this, you cannot use regular expression.

You may try this

req.res=res;
req.on("data", onPosting).on("end", onPosted);

where onPosting and onPosted are defined as below:

function onPosting(data){
  if (this.data){
      this.data.fill(data, this.dataIndex);
      this.dataIndex += data.length;
  } else { 
      var contentLength = +this.headers["content-length"];
      if (data.length === contentLength){
          this.data = data;
      } else {
          this.data = Buffer.alloc(contentLength);
          this.data.fill(data);
          this.dataIndex = data.length;
      }
  }
}

function onPosted(){
  var boundary = extract(this.headers["content-type"], " boundary=");
  var form = parseForm(boundary, this.data);
  console.log(form);
  this.res.end("Data Posted.");
}

And 2 more functions to help parsing the form-data (allow multiple files) to an object:

function extract(arr, start, end){
  var useIndex = typeof start === "number",
      i,
      j;
  if (useIndex){
      i = start;
     if (end){
          j = arr.indexOf(end, i);
          return (j === -1) ? ["", -1] : [ (i === j) ? "" : arr.slice(i, j), j + end.length];
      } else return arr.slice(i);
  } else {
      i = arr.indexOf(start);
      if (i !== -1){
          i += start.length;
          if (end){
              j = arr.indexOf(end, i);
              if (j !== -1) return arr.slice(i, j);
          } else return arr.slice(i);
      }
      return "";
  }
}

function parseForm(boundary, data){
  var form = {},
      delimiter = Buffer.from("\r\n--" + boundary),
      body = extract(data, "--" + boundary + "\r\n"),
      CR = Buffer.from("\r\n\r\n"),
      i = 0,
      head,
      name,
      filename,
      value,
      obj;
  if (body) {
      while (i !== -1){
          [head, i] = extract(body, i, CR);
          name = extract(head, '; name="', '"').toString();
          filename = extract(head, '; filename="', '"').toString();
          [value, i] = extract(body, i, delimiter);
          if (name){
              obj = filename ? {filename, value} : {value};
              if (form.hasOwnProperty(name)){ // multiple 
                  if (Array.isArray(form[name])){
                      form[name].push(obj);
                  } else {
                      form[name] = [form[name], obj];
                  }
              } else {
                  form[name] = obj;
              }
          }
          if (body[i] === 45 && body[i + 1] === 45) break; // "--"
          if (body[i] === 13 && body[i + 1] === 10){
              i += 2; // "\r\n"
          } else {
              //error
          }
      }
  }
  return form;
}

来源：https://stackoverflow.com/questions/46629086/node-js-file-upload-server-without-third-party-module