Internationalization support
Node.js allows you to include the ICU library at build time from the source code, with several available options.
Reference:
Internationalization support
ICU-TC
CommonJS Modules
CommonJS is the original module system used in Node.js. What I found interesting here is the caching mechanism — it's handled differently in build-in modules and others.:
Modules are cached after the first time they are loaded. This means (among other things) that every call to require('foo') will get exactly the same object returned, if it would resolve to the same file. Built-in modules can be identified using the node: prefix, in which case it bypasses the require cache. For instance, require('node:http') will always return the built in HTTP module, even if there is require.cache entry by that name.
Reference:
Cache
Modules: ECMAScript modules
Node.js uses CommonJS by default, but I usually don't pay attention to the module type. I always use import and export in the ESM style. So, what’s happening under the hood?
Let’s take a look:
CommonJS modules consist of a module.exports object which can be of any type. To support this, when importing CommonJS from an ECMAScript module, a namespace wrapper for the CommonJS module is constructed, which always provides a default export key pointing to the CommonJS module.exports value. These CommonJS namespace objects also provide the default export as a 'module.exports' named export, (...). When importing a CommonJS module, it can be reliably imported using the ES module default import or its corresponding sugar syntax
import { default as cjs } from 'cjs';
// Identical to the above
import cjsSugar from 'cjs';
console.log(cjs);
console.log(cjs === cjsSugar);
// Prints:
// <module.exports>
// true
The example above shows how it works. Using import with a CommonJS module is just syntactic sugar. By the way, if you're interested in using require within ESM modules, check out the reference below.
Reference:
CommonJS Namespaces
require(esm) in Node.js