Node's ESM specifier resolution does not support all default behavior of the CommonJS loader. One of the behavior differences is automatic resolution of file extensions and the ability to import directories that have an index file.

Use this loader to enable automatic extension resolution and importing from directories that include an index file, like this:

import file from './file'; // Where ./file is ./file.js or ./file.mjs
import index from './folder'; // Where ./folder is ./folder/index.js or ./folder/index.mjs

This loader also applies these automatic resolution rules to the program entry point passed to node on the command line:

$ node index.mjs
success!
$ node index # Failure!
Error: Cannot find module
$ node --loader=./loader.js index
success!

Uh oh!