How To Use An ES6 Import In Node.js?

To use an ES6 import in Node.js, you need to make some configurations to support ES6 modules. While Node.js was originally built around the CommonJS module system (require() and module.exports), modern JavaScript development prefers using the ES6 module syntax (import and export). Node.js now supports ES6 modules, but enabling and using them requires specific steps.

The import statement is used to import modules exported by some other module. A module is a file that contains a piece of reusable code. The import modules are in strict mode whether it is declared or not.

Syntax

import name from 'module-name';

Below are two approaches to use the ES6 import in NodeJS:

Different Ways to Use ES6 Import in JavaScript

Here we have covered all possible cases for using ES6 import statements in Node.js

Node.js doesn't support ES6 import directly. If we try to use import for importing modules directly in Node.js it will throw out the error.

For example, if we try to import express module by writing import express from 'express' Node.js will throw an error as follows:

To handle this issue, we use ES6 import. Let's see how to use ES6 import in Node.js with examples.

Node.js has experimental support for ES modules. There are two methods to use ES6 import statement in Node.js. We two methods given below

Approach 1: By changing content of package.json file

To enable the use of ES6, we need to make some changes to the package.json file. Before following the steps make sure that Node.js is installed.

To use ES6 imports in Node.js,

• set "type": "module" in your package.json file.
• Use the import statement to include modules, ensuring file extensions like .js are explicitly specified.

Adding this enables ES6 modules. The package.json file should look like this:

//package.json

{
    "name": "index",
    "version": "1.0.0",
    "description": "",
    "main": "index.js",
    "type": "module",
    "scripts": {
        "test": "echo \"Error: no test specified\" && exit 1"
    },
    "keywords": [],
    "author": "",
    "license": "ISC",
    "dependencies": {
        "express": "^4.17.1"
    }
}

Example: Create a file index.js and write the program using ES6 import. For example, let's try to import express in index.js file

//index.js

import express from 'express';
const app = express();

app.get('/', (req, res) => {
    res.send('GeeksforGeeks');
})
const PORT = 5000;

app.listen(PORT, () => {
    console.log(`Running on PORT ${PORT}`);
})

Now run the index.js file by typing node --experimental-modules index.js in the terminal. 

Output:

Approach 2: By using the esm module

We can also enable ES6 import by installing esm module.

Step to install esm: write the following command.

npm install esm

For Node versions older than 12: If we are using the file with .mjs extension then we don't have to add "type": "module" in the package.json file. We can directly write the program and can execute it by typing node --experimental-modules index.mjs in the terminal.

For newer node versions we can directly write node index.mjs to execute the task.

Now, when using a file with .mjs extension the package.json file will look like this:

// package.json when using .mjs file

{
    "name": "index",
    "version": "1.0.0",
    "description": "",
    "main": "index.js",
    "scripts": {
        "test": "echo \"Error: no test specified\" && exit 1"
    },
    "keywords": [],
    "author": "",
    "license": "ISC",
    "dependencies": {
        "esm": "^3.2.25",
        "express": "^4.17.1"
    }
}

Example: Create a file index.mjs and write the program using ES6 import.

//index.mjs

import express from 'express';
const app = express();

app.get('/', (req, res) => {
    res.send('GeeksforGeeks');
})
const PORT = 5000;
app.listen(PORT, () => {
    console.log(`Running on PORT ${PORT}`);
})

Note: In the file server.js, we are importing the index.js file which holds the actual program which needs to be executed. 

node index.mjs

Output:

Advantages of using import in place of require in Node

• Import helps in selectively loading the pieces of code that are required which helps in saving memory.
• In case of require loading is synchronous whereas import can be asynchronous so it performs better than required.

Conclusion

ES6 or ECMAScript 6 is designed for JavaScript language standardization. Using import statements in Node.js would earlier give an error, but after enabling ES6, we can easily use import statements in Node.js.

This tutorial, explains how to use ES6 import in Node.js. We have explained 2 ways to use import in Node.js with examples. Now easily import and export modules between files.