Skip to content

Commit f8e0259

Browse files
Mutesa-Cedricnicojs
authored andcommitted
docs: provide README for jest-haste-map package (jestjs#14613)
1 parent f04118d commit f8e0259

1 file changed

Lines changed: 92 additions & 0 deletions

File tree

packages/jest-haste-map/README.md

Lines changed: 92 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,92 @@
1+
# jest-haste-map
2+
3+
`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.
4+
5+
## why jest-haste-map ?
6+
7+
- **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.
8+
- **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.
9+
- **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.)
10+
- **File system watching:** jest-haste-map can watch the file system for changes. This is useful for building interactive tools, such as watch mode.
11+
12+
## Installation
13+
14+
with npm :
15+
16+
```bash
17+
npm install jest-haste-map --save-dev
18+
```
19+
20+
with yarn :
21+
22+
```bash
23+
yarn add jest-haste-map --dev
24+
```
25+
26+
## usage
27+
28+
`jest-haste-map` is compatible with both `ES modules` and `CommonJS`
29+
30+
### simple usage
31+
32+
```javascript
33+
const map = new HasteMap.default({
34+
// options
35+
});
36+
```
37+
38+
### Example usage (get all files with .js extension in the project)
39+
40+
```javascript
41+
import HasteMap from 'jest-haste-map';
42+
import os from 'os';
43+
import {dirname} from 'path';
44+
import {fileURLToPath} from 'url';
45+
46+
const root = dirname(fileURLToPath(import.meta.url));
47+
48+
const map = new HasteMap.default({
49+
id: 'myproject', //Used for caching.
50+
extensions: ['js'], // Tells jest-haste-map to only crawl .js files.
51+
maxWorkers: os.availableParallelism(), //Parallelizes across all available CPUs.
52+
platforms: [], // This is only used for React Native, you can leave it empty.
53+
roots: [root], // Can be used to only search a subset of files within `rootDir`
54+
retainAllFiles: true,
55+
rootDir: root, //The project root.
56+
});
57+
58+
const {hasteFS} = await map.build();
59+
60+
const files = hasteFS.getAllFiles();
61+
62+
console.log(files);
63+
```
64+
65+
### options
66+
67+
| Option | Type | Required | Default Value |
68+
| ---------------------- | ------------------- | -------- | ------------- |
69+
| cacheDirectory | string | No | `os.tmpdir()` |
70+
| computeDependencies | boolean | No | `true` |
71+
| computeSha1 | boolean | No | `false` |
72+
| console | Console | No | - |
73+
| dependencyExtractor | string \| null | No | `null` |
74+
| enableSymlinks | boolean | No | `false` |
75+
| extensions | Array<string> | Yes | - |
76+
| forceNodeFilesystemAPI | boolean | Yes | - |
77+
| hasteImplModulePath | string | Yes | - |
78+
| hasteMapModulePath | string | Yes | - |
79+
| id | string | Yes | - |
80+
| ignorePattern | HasteRegExp | No | - |
81+
| maxWorkers | number | Yes | - |
82+
| mocksPattern | string | No | - |
83+
| platforms | Array<string> | Yes | - |
84+
| resetCache | boolean | No | - |
85+
| retainAllFiles | boolean | Yes | - |
86+
| rootDir | string | Yes | - |
87+
| roots | Array<string> | Yes | - |
88+
| skipPackageJson | boolean | Yes | - |
89+
| throwOnModuleCollision | boolean | Yes | - |
90+
| useWatchman | boolean | No | `true` |
91+
92+
For more, you can check [github](https://github.com/jestjs/jest/tree/main/packages/jest-haste-map)

0 commit comments

Comments
 (0)