Awesome

Description

A very fast streaming multipart parser for node.js.

Benchmarks can be found here.

Requirements

node.js -- v10.0.0 or newer

Install

npm install dicer

Examples

Parse an HTTP form upload

const { inspect } = require('util');
const http = require('http');

const Dicer = require('dicer');

// Quick and dirty way to parse multipart boundary
const RE_BOUNDARY =
  /^multipart\/.+?(?:; boundary=(?:(?:"(.+)")|(?:([^\s]+))))$/i;
const HTML = Buffer.from(`
  <html><head></head><body>
    <form method="POST" enctype="multipart/form-data">
      <input type="text" name="textfield"><br />
      <input type="file" name="filefield"><br />
      <input type="submit">
    </form>
  </body></html>
`);
const PORT = 8080;

http.createServer((req, res) => {
  let m;
  if (req.method === 'POST'
      && req.headers['content-type']
      && (m = RE_BOUNDARY.exec(req.headers['content-type']))) {
    const d = new Dicer({ boundary: m[1] || m[2] });

    d.on('part', (p) => {
      console.log('New part!');
      p.on('header', (header) => {
        for (const h in header) {
          console.log(
            `Part header: k: ${inspect(h)}, v: ${inspect(header[h])}`
          );
        }
      });
      p.on('data', (data) => {
        console.log(`Part data: ${inspect(data.toString())}`);
      });
      p.on('end', () => {
        console.log('End of part\n');
      });
    });
    d.on('finish', () => {
      console.log('End of parts');
      res.writeHead(200);
      res.end('Form submission successful!');
    });
    req.pipe(d);
  } else if (req.method === 'GET' && req.url === '/') {
    res.writeHead(200);
    res.end(HTML);
  } else {
    res.writeHead(404);
    res.end();
  }
}).listen(PORT, () => {
  console.log(`Listening for requests on port ${PORT}`);
});

API

Dicer is a Writable stream

Dicer (special) events

finish() - Emitted when all parts have been parsed and the Dicer instance has been ended.
part(< PartStream >stream) - Emitted when a new part has been found.
preamble(< PartStream >stream) - Emitted for preamble if you should happen to need it (can usually be ignored).
trailer(< Buffer >data) - Emitted when trailing data was found after the terminating boundary (as with the preamble, this can usually be ignored too).

Dicer methods

(constructor)(< object >config) - Creates and returns a new Dicer instance with the following valid config settings:
- boundary - string - This is the boundary used to detect the beginning of a new part.
- headerFirst - boolean - If true, preamble header parsing will be performed first.
- maxHeaderPairs - integer - The maximum number of header key=>value pairs to parse Default: 2000 (same as node's http).
setBoundary(< string >boundary) - (void) - Sets the boundary to use for parsing and performs some initialization needed for parsing. You should only need to use this if you set headerFirst to true in the constructor and are parsing the boundary from the preamble header.

PartStream is a Readable stream

PartStream (special) events

header(< object >header) - An object containing the header for this particular part. Each property value is an array of one or more string values.