davecombs / fast-resolve-package

a special purpose fast memoizing way to resolve a node modules package.json

resolve-package-path

This project is special-purpose, made to resolve package.json files for:

• a given module name and basedir or
• a given basedir

It cannot and does not resolve anything else.

To achieve its file-resolution performance, it does two specific things:

• It memoizes results identically to node's require. Specifically, for a given moduleName and baseDir it will, for the duration of the process, always return the exact same response.

• It re-implements the parts of require.resolve needed to resolve package.json files ONLY. This removes unneeded I/O. (based on @davecombs approach)

Usage

yarn add resolve-package-path

const resolvePackagePath = require('resolve-package-path');

resolvePackagePath('rsvp', 'base-dir/to/start/the/node_resolution-algorithm-from') // => /path/to/rsvp.json or null

const { findUpPackagePath } = resolvePackagePath;
findUpPackagePath('base-dir/to/start') // => path/to/package.json or null

Advanced usage

Preserve Symlinks

Node supports --preserve-symlinks and NODE_PRESERVE_SYMLINKS=1 for compatibility this library respects these.

Disable default caching

Although by default resolve-package-path caches or memoizes results, this feature can be disabled:

const resolvePackagePath = require('resolve-package-path');

resolvePackagePath('rsvp', 'base-dir/to/start/the/node_resolution-algorithm-from', false) // => uncached result /path/to/rsvp.json or null

const { findUpPackagePath } = resolvePackagePath;
findUpPackagePath('base-dir/to/start', false) // => path/to/package.json or null

Purge the cache

const resolvePackagePath = require('resolve-package-path');
resolvePackagePath._resetCache();

Provide an alternative cache

In some advanced circumtances, you may want to gain access to the cache to share between more systems. In that case, a cache instance of the following form can be provided as a third argument:

cache = {
  RESOLVED_PACKAGE_PATH: new Map(),
  REAL_FILE_PATH: new Map(),
  REAL_DIRECTORY_PATH: new Map(),
};
findUpCache = new Map();

const resolvePackagePath = require('resolve-package-path');
resolvePackagePath('rsvp', 'path/to/start/from', cache);

const { findUpPackagePath } = resolvePackagePath;
findUpPackagePath('base-dir/to/start', findUpCache) // => path/to/package.json or null

Use internal helper functions

For consumers who also do getRealFilePath or getRealDirectoryPath calls on relevant paths, we expose them as utilities. These utilties ensure identical functionality to resolve-package-path, and a shared cache, which may help reduce IO.