🏡 Back Home

Javascript Modules

Tags: #🌲evergreen
Links: Frontend Development | Javascript

---

Javascript has several ways to handle modules and not always intuitive.

Exporting

Export default can only be used once per file:

const onlyOne = 1;
export default { onlyOne }

You can have multiple exports.

const one = 1
const two = 2

export { one }
export { two }

Importing

Default lib is the first one, but the order of the remaining ones don't matter.

import { defaultFirst, two, one } from './lib';

You can also use named imports (specifying a path to an object) so that you only import the slice you need from that module.

CommonJS import and export

Since NodeJS uses CommonJS, the old way (before ES6) uses a different syntax and has different behavior [^2].

Exporting

function hello() {
	return 'hello';
}
function bye() {
	return 'bye';
}

module.exports = {hello, bye};
// or module.exports = hello;

Importing

const hello = require('./greetings');
greetings.hello();
greetings.bye();

One advantage when using require is that you can import a module anywhere and use a variable to compose the name. On the other hand, ES6 importing are always top-level and require fixed names.

[1]: 📘 (MTL) Curso React Native
[2]: javascript - Using Node.js require vs. ES6 import/export - Stack Overflow