How can I use an ES6 import in Node.js?

412

I'm trying to get the hang of ES6 imports in Node.js and am trying to use the syntax provided in this example:

Cheatsheet Link

I'm looking through the support table, but I was not able to find what version supports the new import statements (I tried looking for the text import/require). I'm currently running Node.js 8.1.2 and also believe that since the cheatsheet is referring to .js files it should work with .js files.

As I run the code (taken from the cheatsheet's first example):

import { square, diag } from 'lib';

I get the error:

SyntaxError: Unexpected token import.

Reference to library I'm trying to import:

//------ lib.js ------
export const sqrt = Math.sqrt;
export function square(x) {
    return x * x;
}
export function diag(x, y) {
    return sqrt(square(x) + square(y));
}

What am I missing and how can I get node to recognize my import statement?

This question is tagged with node.js es6-modules

~ Asked on 2017-08-24 06:11:09

The Best Answer is


399

Node.js has included experimental support for ES6 support. Read more about here: https://nodejs.org/docs/latest-v13.x/api/esm.html#esm_enabling.

TLDR;

Node.js >= v13

It's very simple in Node.js 13 and above. You need to either:

  • Save the file with .mjs extension, or
  • Add { "type": "module" } in the nearest package.json.

You only need to do one of the above to be able to use ECMAScript modules.

Node.js <= v12

If you are using Node.js version 8-12, save the file with ES6 modules with .mjs extension and run it like:

node --experimental-modules my-app.mjs

~ Answered on 2017-08-24 06:34:43


296

You can also use npm package called esm which allows you to use ES6 modules in Node.js. It needs no configuration. With esm you will be able to use export/import in your JavaScript files.

Run the following command on your terminal

yarn add esm

or

npm install esm

After that, you need to require this package when starting your server with node. For example if your node server runs index.js file, you would use the command

node -r esm index.js

You can also add it in your package.json file like this

{
  "name": "My-app",
  "version": "1.0.0",
  "description": "Some Hack",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "node -r esm index.js"
  },

}

Then run this command from the terminal to start your node server

npm start

Check this link for more details.

~ Answered on 2019-01-08 10:43:49


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