resolve-mjs

resolve-mjs is a Node.js loader module that allows you to use legacy resolve semantics when importing .mjs ECMAScript modules.

Motivation

Newer versions of Node.js offer native support for ECMAScript import/export loading semantics. This is fantastic, but the maintainers have decided not to support NODE_PATH as part of the resolution algorithm used to locate imported modules (there is most likely a good reason for this, but it is one that I am not aware of).

We use NODE_PATH liberally across our organization to keep our require references clean, so the fact that it's not supported by import has been an impediment to our adoption of native ECMAScript modules. Or at least it was, before we found out you can write custom loader hooks to resolve imports. Now we can have our local dependencies cake and import it too. 🍰

Usage

While ECMAScript modules are considered experimental, you'll need to use the --experimental-modules flag. Additionally, you must pass the --loader resolve-mjs option when running node.

Install It (globally, if you're into that)

npm install [-g] resolve-mjs

Use It

node --experimental-modules --loader resolve-mjs app/index.js

Protip If you install resolve-mjs globally, you can add --experimental-modules --loader resolve-mjs to the NODE_OPTIONS environment variable in order to use it without having to add the flags each time you run node

Behavior

resolve-mjs should not interfere with any import statements that already work with the current import implementation - it will first attempt to resolve the import using the default resolver. Only when that fails to return a valid module will it fallback to locating the module with require semantics.