You try to use ES2015 export/import statements in Node.js and get slapped with “Unexpected Token Export”. There’s a reason this happens. Let’s look at why.

Module syntax

JavaScript has multiple module syntaxes: CommonJS, ES6/ES2015 modules, AMD (Asynchronous Module Definition), and a few others.

So you’ve just picked up ES2015. You’ve learnt about the module system with its shiny export/import statements. You create a class (because hey, that’s another thing you just learnt) and try to export it for reuse in your main application file:

// hero.class.js
export class Hero {
  constructor(name) {
    this.name = name;
  }
}

// app.js
import { Hero } from './hero.class';
const superman = new Hero('Superman');

Run it. Boom: ‘unexpected token “export”’.

The reason’s simple. Node.js uses CommonJS module syntax, which expects two different keywords: require() and module.exports.

You’ve got two options. First, rewrite the code to use CommonJS:

// hero.class.js
class Hero {
  constructor(name) {
    this.name = name;
  }
}

module.exports = Hero;

// app.js
const Hero = require('./hero.class');
const superman = new Hero('Superman');

But if you’ve got a large codebase, rewriting everything might not be practical.

Transpile using Babel

The other option: transpile the export/import syntax using Babel.

Install the appropriate Babel plugin: npm i --save-dev transform-es2015-modules-commonjs.

Then transpile your files (assuming Babel’s installed globally): babel --plugin transform-es2015-modules-commonjs *.js -d build.

You could also specify this plugin in a .babelrc config file instead.

Running that command creates a build folder with two JavaScript files containing:

// hero.class.js
'use strict';
Object.defineProperty(exports, '__esModule', {
  value: true,
});
class Hero {
  constructor(name) {
    this.name = name;
  }
}
exports.Hero = Hero;

// app.js
('use strict');
var _class = require('./hero.class');
const superman = new _class.Hero('Superman');

Babel’s automatically converted the code to CommonJS-style modules.