DEPRECATED - node.js v0.6 has a built-in ZLIB API

deflate -- gzip, zlib, and deflate for node.js

Streaming DEFLATE (RFC 1951), ZLIB (RFC 1950) and GZIP (RFC 1952) compression and expansion for node.js.

uses native zlib.

Install

npm install deflate

or from source:

git clone git://github.com/jahewson/node-deflate.git
cd node-deflate
./build.sh

Examples

You'll need to start with:

var deflate = require('deflate');

Buffer (Synchronous)

Synchronously deflate a Buffer which contains all data to be compressed:

var gzip = deflate.deflateSync(fs.ReadFileSync('example.txt'));

Synchronously inflate a Buffer which contains all compressed data:

var data = deflate.inflateSync(fs.ReadFileSync('example.gz'));

Stream (Asynchronous)

Any ReadableStream can be wrapped with a DeflateStream, which we can pipe into a WritableStream.

// wrap input stream with deflate
var input = fs.createReadStream('example.gz');
input = deflate.createDeflateStream(input);

// pipe to output stream
var output = fs.createWriteStream('example.txt');
input.pipe(output);

Any ReadableStream can be wrapped with an InflateStream, which we can pipe into a WritableStream.

// wrap input stream with inflate
var input = fs.createReadStream('example.bmp');
input = deflate.createInflateStream(input);

// pipe to output stream
var output = fs.createWriteStream('example.gz');
input.pipe(output);

Low-level API

If the Stream interface doesn't meet your needs, you can access the low-level API directly, via the Flater class. See the implementation of DelateStream and InflateStream to learn how to use the low-level API. All low-level functions are synchronous.

Options

deflate(buffer, level=6)

Deflates a gzip formatted Buffer. level sets the compression level from 0 (uncompressed) to 9 (highly compressed), a smaller number is faster.

deflate(buffer, format='gzip', level=6)

Deflates a buffer.

format can be gzip, zlib, or deflate.

level sets the compression level from 0 (uncompressed) to 9 (highly compressed), a smaller number is faster.

createDeflateStream(readStream, level=6)

Creates a Stream which wraps readStream to deflates gzip content.

level sets the compression level from 0 (uncompressed) to 9, a smaller number is faster.

createDeflateStream(readStream, format='gzip', level=6, bufferSize=131072)

Creates a Stream which wraps readStream to deflate its content.

format can be gzip, zlib, or deflate.

level sets the compression level from 0 (uncompressed) to 9 (highly compressed), a smaller number is faster.

bufferSize is the size of the output buffer in bytes. Output data is buffered until it reaches this size, with the exception of the final chunk. The default is 128K.

inflate(buffer, format='gzip')

Inflates a Buffer.

format can be gzip, zlib, or deflate.

createInflateStream(readStream, format='gzip')

Creates a Stream which wraps readStream to inflate its content.

format can be gzip, zlib, or deflate.

Tests

Tests require nodeunit, you can run them all with:

cd node-deflate
nodeunit test

Background

There are many gzip modules for node.js, some just wrap the command-line gzip/gunzip, others wrap zlib, but none are mature or well-maintained, so I decided to invest some time to write node-deflate. Hopefully you'll find it useful.

Acknowledgements

The starting point for node-deflate was the zlib Usage Example public domain C code by Mark Adler (see Adler32).