Sign Up for Free

RunKit +

Try any Node.js package right in your browser

This is a playground to test code. It runs a full Node.js environment and already has all of npm’s 400,000 packages pre-installed, including dicer with all npm packages installed. Try it out:

var dicer = require("dicer")

This service is provided by RunKit and is not affiliated with npm, Inc or the package authors.

dicer v0.3.0

A very fast streaming multipart parser for node.js


A very fast streaming multipart parser for node.js.

Benchmarks can be found here.



npm install dicer


  • Parse an HTTP form upload
var inspect = require('util').inspect,
    http = require('http');

var Dicer = require('dicer');

    // quick and dirty way to parse multipart boundary
var RE_BOUNDARY = /^multipart\/.+?(?:; boundary=(?:(?:"(.+)")|(?:([^\s]+))))$/i,
    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">\
    PORT = 8080;

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

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


Dicer is a WritableStream

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 ReadableStream

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.


RunKit is a free, in-browser JavaScript dev environment for prototyping Node.js code, with every npm package installed. Sign up to share your code.
Sign Up for Free