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jest-haste-map
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# jest-haste-map | ||
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`jest-haste-map` is a module used by Jest, a popular JavaScript testing framework, to create a fast lookup of files in a project. It helps Jest efficiently locate and track changes in files during testing, making it particularly useful for large projects with many files. | ||
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## why jest-haste-map ? | ||
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- **Parallel crawling and analysis:** jest-haste-map crawls the entire project, extracts dependencies, and analyzes files in parallel across worker processes.This can significantly improve the performance of the map building process. | ||
- **Cached file system:** jest-haste-map keeps a cache of the file system in memory and on disk. This allows for fast file related operations, such as resolving module imports and checking for changes. | ||
- **Minimal work**: jest-haste-map only does the minimal amount of work necessary when files change. (If you are using [watchman](https://facebook.github.io/watchman/) (recommended for large projects), Jest will ask watchman for changed files instead of crawling the file system. This is very fast even if you have tens of thousands of files.) | ||
- **File system watching:** jest-haste-map can watch the file system for changes. This is useful for building interactive tools, such as watch mode. | ||
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## Installation | ||
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with npm : | ||
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```bash | ||
npm install jest-haste-map --save-dev | ||
``` | ||
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with yarn : | ||
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```bash | ||
yarn add jest-haste-map --dev | ||
``` | ||
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## usage | ||
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`jest-haste-map` is compatible with both `ES modules` and `CommonJS` | ||
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### simple usage | ||
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```javascript | ||
const map = new HasteMap.default({ | ||
// options | ||
}); | ||
``` | ||
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### Example usage (get all files with .js extension in the project) | ||
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```javascript | ||
import HasteMap from 'jest-haste-map'; | ||
import os from 'os'; | ||
import {dirname} from 'path'; | ||
import {fileURLToPath} from 'url'; | ||
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const root = dirname(fileURLToPath(import.meta.url)); | ||
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const map = new HasteMap.default({ | ||
id: 'myproject', //Used for caching. | ||
extensions: ['js'], // Tells jest-haste-map to only crawl .js files. | ||
maxWorkers: os.availableParallelism(), //Parallelizes across all available CPUs. | ||
platforms: [], // This is only used for React Native, you can leave it empty. | ||
roots: [root], // Can be used to only search a subset of files within `rootDir` | ||
retainAllFiles: true, | ||
rootDir: root, //The project root. | ||
}); | ||
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const {hasteFS} = await map.build(); | ||
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const files = hasteFS.getAllFiles(); | ||
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console.log(files); | ||
``` | ||
### options | ||
| Option | Type | Required | Default Value | | ||
| ---------------------- | ------------------- | -------- | ------------- | | ||
| cacheDirectory | string | No | `os.tmpdir()` | | ||
| computeDependencies | boolean | No | `true` | | ||
| computeSha1 | boolean | No | `false` | | ||
| console | Console | No | - | | ||
| dependencyExtractor | string \| null | No | `null` | | ||
| enableSymlinks | boolean | No | `false` | | ||
| extensions | Array<string> | Yes | - | | ||
| forceNodeFilesystemAPI | boolean | Yes | - | | ||
| hasteImplModulePath | string | Yes | - | | ||
| hasteMapModulePath | string | Yes | - | | ||
| id | string | Yes | - | | ||
| ignorePattern | HasteRegExp | No | - | | ||
| maxWorkers | number | Yes | - | | ||
| mocksPattern | string | No | - | | ||
| platforms | Array<string> | Yes | - | | ||
| resetCache | boolean | No | - | | ||
| retainAllFiles | boolean | Yes | - | | ||
| rootDir | string | Yes | - | | ||
| roots | Array<string> | Yes | - | | ||
| skipPackageJson | boolean | Yes | - | | ||
| throwOnModuleCollision | boolean | Yes | - | | ||
| useWatchman | boolean | No | `true` | | ||
For more, you can check [github](https://github.com/jestjs/jest/tree/main/packages/jest-haste-map) |