ModuleUtilHost

A helper class for resolving paths to libraries and modules

Installation

Simply do: npm install @wessberg/moduleutil.

What is it

This is a service that can resolve the absolute paths to both files within a Typescript/Javascript project as well as entry files within libraries located in node_modules. If you feed it with the path: babel-core, it will look for a library named babel-core within the nearest node_modules folder and resolve the entry point by parsing the package.json file within it. It will always resolve to an entry point that uses ES modules if necessary, otherwise it will use the entry point listed in the main field.

It can also compute absolute paths to modules within your project (i.e. compute absolute paths from relative imports).

Usage

const moduleUtil = new ModuleUtilHost(fileLoader, pathUtil);
moduleUtil.resolvePath("babel-core"); // /Users/<computer_name>/folder/node_modules/babel-core/index.js
moduleUtil.resolvePath("./foo"); // /Users/<computer_name>/folder/foo.ts

Library paths vs module paths

Paths that starts with ./ are determined to be modules within your project and will be resolved from its position within the code base. Otherwise, it will be resolved within node_modules. This behavior mimics Node's resolution algorithm.

Supported extensions

By default, ModuleUtilHost will look for files with any of the following extensions: .ts, .js or .json (in that order). You can pass in additional extensions to the constructor if you please:

const moduleUtil = new ModuleUtilHost(fileLoader, pathUtil, {
	extraExtensions: [".css", ".scss"]
});

Supported package.json fields

By default, ModuleUtilHost will parse the following entry point fields within any package.json file located within node-modules: module, es2015, jsnext:main, main (in that order). You can pass in additional entry point fields to the constructor if you please:

const moduleUtil = new ModuleUtilHost(fileLoader, pathUtil, {
	extraPackageFields: ["browser", "something"]
});

Built-in modules

If ModuleUtilHost receives a path that points to a built-in module such as fs or path, it will simply return that path, rather than attempting to resolve the module within node_modules (which wouldn't make sense since it is built-in) If you know of more built-in modules than the ones provided by the plugin, you can pass them in as an option:

const moduleUtil = new ModuleUtilHost(fileLoader, pathUtil, {
	extraBuiltInModules: ["some-module", "foo"]
});