engine.io-parser

This is the JavaScript parser for the engine.io protocol encoding, shared by both engine.io-client and engine.io.

How to use

Standalone

The parser can encode/decode packets, payloads, and payloads as binary with the following methods: encodePacket, decodePacket, encodePayload, decodePayload.

Example:

const parser = require("engine.io-parser");
const data = Buffer.from([ 1, 2, 3, 4 ]);

parser.encodePacket({ type: "message", data }, encoded => {
  const decodedData = parser.decodePacket(encoded); // decodedData === data
});

With browserify

Engine.IO Parser is a commonjs module, which means you can include it by using require on the browser and package using browserify:

1. install the parser package

   npm install engine.io-parser

2. write your app code

   const parser = require("engine.io-parser");
   
   const testBuffer = new Int8Array(10);
   for (let i = 0; i < testBuffer.length; i++) testBuffer[i] = i;
   
   const packets = [{ type: "message", data: testBuffer.buffer }, { type: "message", data: "hello" }];
   
   parser.encodePayload(packets, encoded => {
     parser.decodePayload(encoded,
       (packet, index, total) => {
         const isLast = index + 1 == total;
         if (!isLast) {
           const buffer = new Int8Array(packet.data); // testBuffer
         } else {
           const message = packet.data; // "hello"
         }
       });
   });

3. build your app bundle

   $ browserify app.js > bundle.js

4. include on your page

   <script src="/path/to/bundle.js"></script>

Features

• Runs on browser and node.js seamlessly
• Runs inside HTML5 WebWorker
• Can encode and decode packets
  • Encodes from/to ArrayBuffer or Blob when in browser, and Buffer or ArrayBuffer in Node

API

Note: cb(type) means the type is a callback function that contains a parameter of type type when called.

Node

• encodePacket

  • Encodes a packet.
  • Parameters
    • Object: the packet to encode, has type and data.
      • data: can be a String, Number, Buffer, ArrayBuffer
    • Boolean: binary support
    • Function: callback, returns the encoded packet (cb(String))

• decodePacket

  • Decodes a packet. Data also available as an ArrayBuffer if requested.
  • Returns data as String or (Blob on browser, ArrayBuffer on Node)
  • Parameters
    • String | ArrayBuffer: the packet to decode, has type and data
    • String: optional, the binary type

• encodePayload

  • Encodes multiple messages (payload).
  • If any contents are binary, they will be encoded as base64 strings. Base64 encoded strings are marked with a b before the length specifier
  • Parameters
    • Array: an array of packets
    • Function: callback, returns the encoded payload (cb(String))

• decodePayload

  • Decodes data when a payload is maybe expected. Possible binary contents are decoded from their base64 representation.
  • Parameters
    • String: the payload
    • Function: callback, returns (cb(Object: packet, Number:packet index, Number:packet total))

Tests

Standalone tests can be run with npm test which will run the node.js tests.

Browser tests are run using zuul. (You must have zuul setup with a saucelabs account.)

You can run the tests locally using the following command:

npm run test:browser

Support

The support channels for engine.io-parser are the same as socket.io:

• irc.freenode.net #socket.io
• Github Discussions
• Website

Development

To contribute patches, run tests or benchmarks, make sure to clone the repository:

git clone git://github.com/socketio/engine.io-parser.git

Then:

cd engine.io-parser
npm ci

See the Tests section above for how to run tests before submitting any patches.

License

MIT