Asset Hash

Asset Hash is a quick wrapper around hashing libraries for efficient and fast hashing of asset files like images, web fonts, etc. By default it uses the cross-platform performance-optimized XXHash-WASM and a Base52 encoding ([a-zA-Z]) which works well for file names and urls and has a larger dictionary than when using traditional hex.

Note: Using the modern XXHash-WASM requires NodeJS >= v16. The module still supports older NodeJS v14 through the usage of the (optional) farmhash module.

Table of Contents

• Installation
  • NPM
  • Yarn
• Speed
• Usage
  • getHash()
  • getHashedName()
  • Class Hasher
  • Webpack Example Config
• License
• Copyright

Installation

NPM

npm install asset-hash

Yarn

yarn add asset-hash

Speed

For speed comparisons of different algorithms we created a small repository containing the source code and some results. Check it out. TLDR: Modern non-cryptographic hashing could be way faster than traditional solutions like MD5 or SHA1. Best algorithms right now for our use cases seems to be XXHash (WASM) and Farmhash. This is why we integrated both while making the WASM powered XXHash the default for improved developer experience.

Usage

There are two main methods: getHash(filePath, options) and getHashedName(filePath, options) and a more traditional class Hasher(options). Both methods return a Promise with there actual hash or hash file name as a result. The class offers the pretty traditional methods update(data) and digest(options) to send data or to retrieve the hash.

Options:

• algorithm: Any valid hashing algorithm e.g. xxhash64 (default), xxhash32, farmhash32, farmhash64, sha1, md5, ...
• encoding: Any valid encoding for built-in digests hex, base64, base62, ...
• maxLength: Maximum length of returned digest. Keep in mind that this increases collision probability.

Please note:

• farmhash32 and farmhash64 do not support streaming. When using the file hashing APIs it's collecting all data first before producing the hash. This might result in higher memory usage!

getHash()

import { getHash } from "asset-hash"
...

const hash = await getHash("./src/fixtures/font.woff")
console.log("Hash:", hash) => "Hash: fXQovA"

getHashedName()

The hashed file name replaces the name part of the file with the hash while keeping the file extension.

import { getHashedName } from "asset-hash"
...

const hashedName = await getHashedName("./src/fixtures/font.woff")
console.log("Hashed Filename:", hashedName) => "Hashed Filename: fXQovA.woff"

Class Hasher

import { Hasher } from "asset-hash"
const hasher = new Hasher()
hasher.update(data)
console.log("Hashed Data:", hasher.digest()) => "Hashed Data: XDOPW"

Webpack Example Config

You can use the powerful hashing of AssetHash inside Webpack as well. This leads to a) better performance and b) shorter hashes. Wo correctly support the WASM-based hashes your Webpack configuration should be created using an async function.

Here is an example configuration:

import { Hasher, initHashClasses } from "asset-hash"

module.exports = async () => {
  await initHashClasses()

  return {
    ...
    output: {
      hashFunction: Hasher,
      hashDigest: "base52",
      hashDigestLength: 8
    }
    ...
  }
}

License

Apache License; Version 2.0, January 2004

Copyright

Copyright 2017-2022
Sebastian Software GmbH