Node.js - SyntaxError: Unexpected token import
I'm shocked esm
hasn't been mentioned. This small, but mighty package allows you to use either import
or require
.
Install esm in your project
$ npm install --save esm
Update your Node Start Script to use esm
node -r esm app.js
esm
just works. I wasted a TON of time with .mjs
and --experimental-modules
only to find out a .mjs
file cannot import a file that uses require
or module.exports
. This was a huge problem, whereas esm
allows you to mix and match and it just figures it out... esm
just works.
Unfortunately, Node.js doesn't support ES6's import
yet.
To accomplish what you're trying to do (import the Express module), this code should suffice
var express = require("express");
Also, be sure you have Express installed by running
$ npm install express
See the Node.js Docs for more information about learning Node.js.
As mentioned in other answers Node JS currently doesn't support ES6 imports.
(As of now, read EDIT 2)
Enable ES6 imports in node js provides a solution to this issue. I have tried this and it worked for me.
Run the command:
npm install babel-register babel-preset-env --save-dev
Now you need to create a new file (config.js) and add the following code to it.
require('babel-register')({
presets: [ 'env' ]
})
// Import the rest of our application.
module.exports = require('./your_server_file.js')
Now you can write import statements without getting any errors.
Hope this helps.
EDIT:
You need to run the new file which you created with above code. In my case it was config.js
. So I have to run:
node config.js
EDIT 2:
While experimenting, I found one easy solution to this issue.
Create .babelrc
file in the root of your project.
Add following (and any other babel presets you need, can be added in this file):
{
"presets": ["env"]
}
Install babel-preset-env
using command npm install babel-preset-env --save
, and then install babel-cli
using command npm install babel-cli -g --save
Now, go to the folder where your server or index file exists and run using: babel-node fileName.js
Or you can run using npm start
by adding following code to your package.json
file:
"scripts": {
"start": "babel-node src/index.js"
}
Node 13+ Since Node 13, you can use either the .mjs
extension, or set {"type": "module"}
in your package.json. You don't need to use the --experimental-modules
flag. Modules is now marked as stable in node.js
Node 12 Since Node 12, you can use either the .mjs
extension, or set "type": "module"
in your package.json. And you need to run node with the --experimental-modules
flag.
Node 9 In Node 9, it is enabled behind a flag, and uses the .mjs
extension.
node --experimental-modules my-app.mjs
While import
is indeed part of ES6, it is unfortunately not yet supported in NodeJS by default, and has only very recently landed support in browsers.
See browser compat table on MDN and this Node issue.
From James M Snell's Update on ES6 Modules in Node.js (February 2017):
Work is in progress but it is going to take some time — We’re currently looking at around a year at least.
Until support shows up natively (now marked stable in Node 13+), you'll have to continue using classic :require
statements
const express = require("express");
If you really want to use new ES6/7 features in NodeJS, you can compile it using Babel. Here's an example server.