What is jest-haste-map?
The jest-haste-map npm package is a utility for building a Haste map, which is a mapping from module names to file paths. It is used by Jest to quickly resolve module dependencies for tests by keeping an in-memory map of all available modules. It can handle duplicate module names and provides a way to query the map for a specific module.
What are jest-haste-map's main functionalities?
Building a Haste Map
This code sample demonstrates how to create a new HasteMap instance with a configuration object, build the map, and then use it to get the module name for a specific file.
const HasteMap = require('jest-haste-map');
const config = {
// These options are required:
roots: ['/path/to/project'],
extensions: ['js', 'json'],
platforms: ['ios', 'android'],
// You can provide additional options:
computeSha1: true,
// other options...
};
const hasteMap = new HasteMap(config);
hasteMap.build().then(map => {
console.log(map.hasteFS.getModuleName('/path/to/project/file.js'));
});
Querying the Haste Map
This code sample shows how to query the built Haste map for the path of a module given its name, platform, and whether it supports the native platform.
hasteMap.build().then(map => {
const modulePath = map.moduleMap.getModule('moduleName', 'platform', 'supportsNativePlatform');
console.log(modulePath);
});
Other packages similar to jest-haste-map
metro
Metro is a JavaScript bundler for React Native applications. It includes a Haste map implementation similar to jest-haste-map, but it is tailored specifically for React Native and includes additional features for bundling and transforming code.
webpack
Webpack is a powerful module bundler for JavaScript applications. While it does not use a Haste map, it provides a similar functionality through its own resolution mechanism, which can handle complex dependency graphs and offers a wide range of plugins for different tasks.
browserify
Browserify is a tool for bundling JavaScript files for usage in the browser. Like webpack, it does not use a Haste map, but it allows developers to require modules in the browser by bundling up all dependencies. It's simpler than webpack and may be more suitable for smaller projects.