jest-haste-map
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.
why jest-haste-map ?
- 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 (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.
Installation
with npm :
npm install jest-haste-map --save-dev
with yarn :
yarn add jest-haste-map --dev
usage
jest-haste-map
is compatible with both ES modules
and CommonJS
simple usage
const map = new HasteMap.default({
});
Example usage (get all files with .js extension in the project)
import HasteMap from 'jest-haste-map';
import os from 'os';
import {dirname} from 'path';
import {fileURLToPath} from 'url';
const root = dirname(fileURLToPath(import.meta.url));
const map = new HasteMap.default({
id: 'myproject',
extensions: ['js'],
maxWorkers: os.availableParallelism(),
platforms: [],
roots: [root],
retainAllFiles: true,
rootDir: root,
});
const {hasteFS} = await map.build();
const files = hasteFS.getAllFiles();
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