80 lines
2.5 KiB
Markdown
80 lines
2.5 KiB
Markdown
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# package-hash
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Generates a hash for an installed npm package, useful for salting caches.
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[AVA](https://github.com/sindresorhus/ava) for example caches precompiled test
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files. It generates a salt for its cache based on the various packages that are
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used when compiling the test files.
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`package-hash` can generate an appropriate hash based on the package location
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(on disk) and the `package.json` file. This hash is salted with a hash
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for the `package-hash` itself.
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`package-hash` can detect when the package-to-be-hashed is a Git repository. In
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the AVA example this is useful when you're debugging one of the packages used to
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compile the test files. You can clone it locally and use `npm link` so AVA can
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find the clone. The hash will include the HEAD (`.git/HEAD`) and its
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corresponding ref (e.g. `.git/refs/heads/master`), any packed refs
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(`.git/packed-refs`), as well as the diff (`git diff`) for any non-committed
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changes. This makes it really easy to test your changes without having to
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explicitly clear the cache in the parent project.
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## Installation
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```console
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$ npm install --save package-hash
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```
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## Usage
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```js
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const packageHash = require('package-hash')
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// Asynchronously:
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const hash = await packageHash(require.resolve('babel-core/package.json'))
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// Synchronously:
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const hash = packageHash.sync(require.resolve('babel-core/package.json'))
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```
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`packageHash()` / `packageHash.sync()` must be called with a file path for an
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existing `package.json` file. To get the path to an npm package it's easiest to
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use `require.resolve('the-name/package.json')`.
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You can provide multiple paths:
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```js
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const hash = await packageHash([
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require.resolve('babel-core/package.json'),
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require.resolve('babel-preset-es2015/package.json')
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])
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```
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An optional salt value can also be provided:
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```js
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const hash = await packageHash(require.resolve('babel-core/package.json'), 'salt value')
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```
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## API
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### `packageHash(paths, salt?)`
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`paths: string | string[]` ➜ can be a single file path, or an array of paths.
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`salt: Array | Buffer | Object | string` ➜ optional. If an `Array` or `Object` (not `null`) it is first converted to a JSON string.
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Returns a promise for the hex-encoded hash string.
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### `packageHash.sync(paths, salt?)`
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`paths: string | string[]` ➜ can be a single file path, or an array of paths.
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`salt: Array | Buffer | Object | string` ➜ optional. If an `Array` or `Object` (not `null`) it is first converted to a JSON string.
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Returns a hex-encoded hash string.
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## Compatibility
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`package-hash` has been tested with Node.js 4 and above, including Windows
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support.
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