HORIZON PROJECT

# engine.io-parser

[![Build Status](https://secure.travis-ci.org/socketio/engine.io-parser.svg)](http://travis-ci.org/socketio/engine.io-parser)

[![NPM version](https://badge.fury.io/js/engine.io-parser.svg)](http://badge.fury.io/js/engine.io-parser)

This is the JavaScript parser for the engine.io protocol encoding,

shared by both

[engine.io-client](https://github.com/socketio/engine.io-client) and

[engine.io](https://github.com/socketio/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`, `encodePayloadAsBinary`, `decodePayloadAsBinary`.

The browser-side parser also includes `encodePayloadAsArrayBuffer` and `encodePayloadAsBlob`.

Example:

```js

var parser = require('engine.io-parser');

var data = new Buffer(5);

for (var i = 0; i < data.length; i++) { data[i] = i; }

parser.encodePacket({ type: 'message', data: data }, function(encoded) {

  var decodedData = parser.decodePacket(encoded); // { type: 'message', data: 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](http://browserify.org/):

1. install the parser package

    ```shell

    npm install engine.io-parser

    ```

1. write your app code

    ```js

    var parser = require('engine.io-parser');

    var testBuffer = new Int8Array(10);

    for (var i = 0; i < testBuffer.length; i++) testBuffer[i] = i;

    var packets = [{ type: 'message', data: testBuffer.buffer }, { type: 'message', data: 'hello' }];

    parser.encodePayload(packets, function(encoded) {

      parser.decodePayload(encoded,

        function(packet, index, total) {

          var isLast = index + 1 == total;

          if (!isLast) {

            var buffer = new Int8Array(packet.data); // testBuffer

          } else {

            var message = packet.data; // 'hello'

          }

        });

    });

    ```

1. build your app bundle

    ```bash

    $ browserify app.js > bundle.js

    ```

1. include on your page

    ```html

    <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`: optional, 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

- `encodeBase64Packet`

    - Encodes a packet with binary data in a base64 string (`String`)

    - **Parameters**

      - `Object`: the packet to encode, has `type` and `data`

      - `Function`: callback, returns the base64 encoded message (`cb(String)`)

- `decodeBase64Packet`

    - Decodes a packet encoded in a base64 string.

    - **Parameters**

      - `String`: the base64 encoded message

      - `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

      - `Boolean`: optional, binary support

      - `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

      - `String`: optional, the binary type

      - `Function`: callback, returns (cb(`Object`: packet, `Number`:packet index, `Number`:packet total))

- `encodePayloadAsBinary`

    - Encodes multiple messages (payload) as binary.

    - **Parameters**

      - `Array`: an array of packets

      - `Function`: callback, returns the encoded payload (`cb(Buffer)`)

- `decodePayloadAsBinary`

    - Decodes data when a payload is maybe expected. Strings are decoded by

      interpreting each byte as a key code for entries marked to start with 0. See

      description of encodePayloadAsBinary.

    - **Parameters**

      - `Buffer`: the buffer

      - `String`: optional, the binary type

      - `Function`: callback, returns the decoded packet (`cb(Object)`)

### Browser

- `encodePayloadAsArrayBuffer`

    - Encodes multiple messages (payload) as binary.

    - **Parameters**

      - `Array`: an array of packets

      - `Function`: callback, returns the encoded payload (`cb(ArrayBuffer)`)

- `encodePayloadAsBlob`

    - Encodes multiple messages (payload) as blob.

    - **Parameters**

      - `Array`: an array of packets

      - `Function`: callback, returns the encoded payload (`cb(Blob)`)

## Tests

Standalone tests can be run with `make test` which will run both node.js and browser tests.

Browser tests are run using [zuul](https://github.com/defunctzombie/zuul).

(You must have zuul setup with a saucelabs account.)

You can run the tests locally using the following command:

```

./node_modules/.bin/zuul --local 8080 -- test/index.js

```

## Support

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

  - irc.freenode.net **#socket.io**

  - [Google Groups](http://groups.google.com/group/socket_io)

  - [Website](http://socket.io)

## Development

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

repository:

```bash

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

```

Then:

```bash

cd engine.io-parser

npm install

```

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

## License

MIT