mogoz

commonjs vs esm

tags: Javascript

The difference

ESM

is a web standard
ESM can consume and use CommonJS modules
node ecosystem as of 2023 has not properly moved to esm , so better to stick w commonjs w node
ESM is made better use of via bundlers for the web. So for web, esm is fine, for node, not so good.
import is an asynchronous (esm)

CommonJS

Not a web standard
CommonJS cannot consume ESM modules easily, it needs extra loader/transpiler or using dynamic imports
Using dynamic import means you need to deal w promises and put things in IIFE
require is synchronous (commonjs)

Modules

modules on the other hand can be only commonjs, or only esm or both. So we need to be aware of that aswell.
eg. jest does don’t work otb on esm or something like that

More brain fry w ts

When writing typescript, you can write something that looks like ESM with import/export, while targeting CJS