package-hash

Generates a hash for an installed npm package, useful for salting caches. AVA for example caches precompiled test files. It generates a salt for its cache based on the various packages that are used when compiling the test files.

package-hash can generate an appropriate hash based on the package location (on disk) and the package.json file. This hash is salted with a hash for the package-hash itself.

package-hash can detect when the package-to-be-hashed is a Git repository. In the AVA example this is useful when you're debugging one of the packages used to compile the test files. You can clone it locally and use npm link so AVA can find the clone. The hash will include the HEAD (.git/HEAD) and its corresponding ref (e.g. .git/refs/heads/master), any packed refs (.git/packed-refs), as well as the diff (git diff) for any non-committed changes. This makes it really easy to test your changes without having to explicitly clear the cache in the parent project.

Installation

$ npm install --save package-hash

Usage

const packageHash = require('package-hash')
 
// Asynchronously:
const hash = await packageHash(require.resolve('babel-core/package.json'))
 
// Synchronously:
const hash = packageHash.sync(require.resolve('babel-core/package.json'))

packageHash() / packageHash.sync() must be called with a file path for an existing package.json file. To get the path to an npm package it's easiest to use require.resolve('the-name/package.json').

You can provide multiple paths:

const hash = await packageHash([
  require.resolve('babel-core/package.json'),
  require.resolve('babel-preset-es2015/package.json')
])

An optional salt value can also be provided:

const hash = await packageHash(require.resolve('babel-core/package.json'), 'salt value')

API

packageHash(paths, salt?)

paths: string | string[] ➜ can be a single file path, or an array of paths.

salt: Array | Buffer | Object | string ➜ optional. If an Array or Object (not null) it is first converted to a JSON string.

Returns a promise for the hex-encoded hash string.

packageHash.sync(paths, salt?)

paths: string | string[] ➜ can be a single file path, or an array of paths.

salt: Array | Buffer | Object | string ➜ optional. If an Array or Object (not null) it is first converted to a JSON string.

Returns a hex-encoded hash string.

Compatibility

package-hash has been tested with Node.js 8 and above, including Windows support.