nodejs / import modules

Question

I don't get the logic of the module conception in nodejs / javascript

Here is my file : circle.js

const circleArea = r => 3.14 * (r ** 2);
const squareArea = s => s * s;
export {circleArea, squareArea};

file testCircle.js

import { circleArea as circle, squareArea } from "./circle.js"
console.log(squareArea(2));

When I run the program node testCircle.js

SyntaxError: Cannot use import statement outside a module

I have found an explanation here :

SyntaxError: Cannot use import statement outside a module

So In have updated my package.json

 "type": "module"

And it works

BUT

then when I want to run another file which require :

const http = require("http");

I got this new error :

ReferenceError: require is not defined

Is there a way to work with both import and require ?

• Quentin: Just use import instead of require.
• user14596364: Can you remove type="module" from 'package.json` and try again ?
• user16540390: @Jaood_xD Your comment is wrong and the link doesn't even mention ES6 modules.
• user16540390: An example for a ES6 module importing an CJS module: stackblitz.com/edit/node-dar2r5?file=index.js
• Jaood_xD: @jabaa my bad, wrong link

Answer 1

Use the extension mjs for ES6 modules without "type": "module" or cjs for Common JS modules with "type": "module". Then you can use both types of modules in one project.

Example 1:

package.json:

{
 "name": "node-starter",
 "version": "0.0.0",
 "scripts": {
 "start": "node index.js"
 },
 "type": "module"
}

index.js:

import { a } from './a.cjs';
a();

a.cjs:

module.exports = {
 a() {
 console.log('Hello World!');
 },
};

Running example: https://stackblitz.com/edit/node-dar2r5

Example 2:

package.json:

{
 "name": "node-starter",
 "version": "0.0.0",
 "scripts": {
 "start": "node index.mjs"
 }
}

index.mjs:

import { a } from './a.js';
a();

a.js:

module.exports = {
 a() {
 console.log('Hello World!');
 },
};

Running example: https://stackblitz.com/edit/node-enengw

• fransua: If I add const http = require("http") in your index.mjs, then I got an error : ReferenceError: require is not defined
• user16540390: @fransua A file is either a CommonJS module or a ES6 module. You can't use require in a ES6 module and you can't use import in a CommonJS module. That means you can't mix require and import in the same file. Use import http from "http"; instead