http-encoding

Part of HTTP Toolkit: powerful tools for building, testing & debugging HTTP(S)

Everything you need to handle HTTP message body content-encoding

This package includes methods to decode & encode all commonly used HTTP content encodings, in a consistent format, usable in both Node.js and browsers.

The supported codecs are:

• Gzip
• Raw deflate (with or without a zlib wrapper)
• Brotli
• Zstandard
• Base64

All encoding names are case-insensitive (although lowercase is generally standard). The 'identity', 'amz-1.0', 'none', 'text', 'binary', 'utf8' and 'utf-8' encodings are all supported as no-op encodings, passed through with no en/decoding at all. Only 'identity' is standard, but the others are all in common use regardless.

Found a codec used in real-world HTTP that isn't supported? Open an issue!

API

The library includes two general methods:

decodeBuffer(body, encoding)

Takes an encoded body buffer and encoding (in the format of a standard HTTP content-encoding header) and returns a promise for a decoded buffer, using the zero to many buffers specified in the header.

The input buffer can be any Uint8Array including a Node Buffer (a subclass of Uint8Array). A node-compatible buffer is always returned.

If any encoding is unrecognized or unavailable then this method will throw an exception.

A decodeBufferSync method is also available for some use cases, but not recommended, as it's less performant and cannot support some encodings (Brotli or Zstandard).

encodeBuffer(body, encoding, { level })

Takes a raw body buffer and a single encoding (a valid HTTP content-encoding name) and returns a promise for an encoded buffer, using the zero to many buffers specified in the header.

The input buffer can be any Uint8Array (including a Node Buffer, which is a Uint8Array subclass) or an ArrayBuffer. A node-compatible buffer is always returned.

If any encoding is unrecognized or unavailable then this method will throw an exception.

Per-codec methods

This library also exports consistent async methods to compress and decompress each of the codecs directly:

• gzip
• gunzip
• deflate
• inflate
• inflateRaw
• brotliCompress
• brotliDecompress
• zstdCompress
• zstdDecompress
• encodeBase64
• decodeBase64

Each method accepts a buffer and returns a promise for a buffer.

Browser usage

To use this in a browser, you'll need to use a bundler (e.g. Webpack) that can include standard Node.js polyfill packages, you may need to install those polyfill packages, and your bundler needs to support bundling WebAssembly (e.g. Webpack v4+).

In Webpack v4 this should all work automatically. In Webpack v5 this will require explicit dependencies and configuration. See this package's own test webpack config and dev dependencies for a working example.

Brotli and Zstandard are only supported in runtime environments that support WebAssembly. All WebAssembly packages are loaded on-demand and only when native methods (e.g. Node's zlib.brotli*) are not available.