asset-hash

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 performance-optimized Metrohash and a Base52 encoding ([a-zA-Z]) which works well for file names and urls and has a larger dictionary than when using hex.

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 cryptographic solutions like MD5 or SHA1. Best algorithm right now for our use cases seems to be MetroHash128. This is why we made it the default.

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:

• hash: Any valid hashing algorithm e.g. metrohash128 (default), metrohash64, xxhash64, xxhash32, 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 collison probability.

For supporting xxhash you have to install the npm module xxhash on your own. Because there are currently issues with Node v12 we decided to remove the direct dependency in this module.

getHash()

import { getHash } from "asset-hash"
getHash("./src/fixtures/font.woff").then((hash) => {
  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"
getHashedName("./src/fixtures/font.woff").then((hashedName) => {
  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. Here is an example configuration:

import { Hasher } from "asset-hash"

...

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

...

For more details please check the official Webpack docs.

License

Apache License; Version 2.0, January 2004

Copyright

Copyright 2017-2019
Sebastian Software GmbH