@agentine/bellows

Drop-in replacement for pako — zlib compression library for Node.js and browsers.

• TypeScript-first — built-in types, no @types/pako needed
• Native delegation — Node.js zlib module + browser CompressionStream
• Zero dependencies
• ESM + CJS dual package with conditional exports
• pako-compatible API — deflate, inflate, gzip, ungzip, streaming classes

Install

npm install @agentine/bellows

Usage

import { deflate, inflate, gzip, ungzip } from '@agentine/bellows';

// Compress
const compressed = deflate('Hello, World!');

// Decompress
const decompressed = inflate(compressed, { to: 'string' });
// => 'Hello, World!'

// Gzip
const gzipped = gzip('Hello, World!');
const original = ungzip(gzipped, { to: 'string' });

Streaming

import { Deflate, Inflate } from '@agentine/bellows';
import { Z_FINISH } from '@agentine/bellows';

const deflater = new Deflate({ level: 9 });
deflater.push(data, Z_FINISH);
if (deflater.err) throw new Error(deflater.msg);
const compressed = deflater.result;

Raw deflate

import { deflateRaw, inflateRaw } from '@agentine/bellows';

const compressed = deflateRaw(input);
const decompressed = inflateRaw(compressed);

Migration from pako

Replace your import:

-import pako from 'pako';
+import * as pako from '@agentine/bellows/compat/pako';

Or use the direct API (same function names):

-import { deflate, inflate } from 'pako';
+import { deflate, inflate } from '@agentine/bellows';

API

Sync Functions

Function	Description
deflate(input, options?)	Compress (zlib format)
deflateRaw(input, options?)	Compress (raw deflate)
gzip(input, options?)	Compress (gzip format)
inflate(input, options?)	Decompress (zlib format)
inflateRaw(input, options?)	Decompress (raw deflate)
ungzip(input, options?)	Decompress (gzip format)

Streaming Classes

• new Deflate(options?) — streaming compression
• new Inflate(options?) — streaming decompression

Both support push(data, flushMode), onData, onEnd, result, err, msg.

Options

Option	Type	Description
level	0-9	Compression level (0=none, 9=best)
windowBits	number	8-15 zlib, -8 to -15 raw, 16+x gzip
memLevel	1-9	Memory usage
strategy	number	Z_DEFAULT_STRATEGY, Z_FILTERED, etc.
dictionary	Uint8Array	Preset dictionary
to	'string'	Return string instead of Uint8Array
chunkSize	number	Streaming chunk size

Constants

All pako/zlib constants are exported: Z_NO_FLUSH, Z_FINISH, Z_OK, Z_STREAM_END, Z_NO_COMPRESSION, Z_BEST_COMPRESSION, Z_DEFAULT_STRATEGY, etc.

Browser Support

The browser build uses the CompressionStream/DecompressionStream API (Chrome 80+, Firefox 113+, Safari 16.4+).

Limitations vs Node.js backend:

• Functions are async (return Promises) — CompressionStream is inherently async
• level, strategy, memLevel, dictionary options are not supported
• Streaming class push() callbacks fire asynchronously

For sync compression in the browser, use the pako compat layer which imports the Node.js backend (suitable for SSR/bundlers with Node.js polyfills).

License

MIT