In Node.js, require and import are two ways to include external modules in your code. Both of them serve the same purpose, but they have some differences that are worth noting.

Require

require is a built-in function in Node.js that allows you to load external modules. It works synchronously, which means that it blocks the execution of the rest of the code until the module is loaded. Here is an example:

const fs = require('fs');
const data = fs.readFileSync('file.txt', 'utf8');
console.log(data);

In this example, we are loading the fs module, which provides a way to interact with the file system. We then use the readFileSync method to read the contents of a file called file.txt. Finally, we log the contents to the console.

Import

import is a newer way to include external modules in your code. It is part of the ES6 (ECMAScript 2015) specification, and it works asynchronously. Here is an example:

import fs from 'fs/promises';
async function readFile() {
  const data = await fs.readFile('file.txt', 'utf8');
  console.log(data);
}
readFile();

In this example, we are using the import statement to load the fs/promises module, which provides a way to interact with the file system using promises. We then define an async function called readFile, which uses the readFile method to read the contents of a file called file.txt. Finally, we log the contents to the console.

Exporting

In addition to loading external modules, you may also want to export your own code as a module that can be used by other parts of your application. There are several ways to do this, depending on the module system you are using.

CommonJS

CommonJS is the module system used by Node.js. To export a module in CommonJS, you can use the module.exports or exports objects. Here is an example:

// module.js
function hello(name) {
  console.log(`Hello, ${name}!`);
}
module.exports = { hello };

// app.js
const module = require('./module');
module.hello('world');

In this example, we define a function called hello in a module called module.js. We then export the function using module.exports. In app.js, we load the module using require, and we call the hello function.

ES6 Modules

ES6 modules are a newer module system that is supported by some browsers and by Node.js with the --experimental-modules flag. To export a module in ES6, you can use the export keyword. Here is an example:

// module.js
function hello(name) {
  console.log(`Hello, ${name}!`);
}
export { hello };

// app.js
import { hello } from './module.js';
hello('world');

In this example, we define a function called hello in a module called module.js. We then export the function using the export keyword. In app.js, we load the module using import, and we call the hello function.

Conclusion