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