node --experimental-modules, requested module does not provide an export named

Question

I've installed Node 8.9.1 (same problem happens in v10.5.0).

I'm trying to use named imports from npm packages in a file with the .mjs

import { throttle } from lodash;

I run:

node --experimental-modules index.mjs

and I get:

SyntaxError: The requested module 'lodash' does not provide an export named 'throttle' at ModuleJob._instantiate (internal/modules/esm/module_job.js:80:21)

--experimental-modules are supposed to stop being experimental in v10 LTS, so why haven't more module authors jumped on the bandwagon?

Answer 1

--experimental-modules does not have support for named exports yet:

--experimental-modules doesn't support importing named exports from a commonjs module (except node's own built-ins).

• https://github.com/apollographql/graphql-tools/issues/913

This is why you are unable to use the syntax:

 import { throttle } from 'lodash';

Instead (for now at least) you have to destruct what you need:

 import lodash from 'lodash';
 const { throttle } = lodash;

Presumably someday Node will add support for all of the ES Module features.

Answer 2

You have to use .mjs extension.

Once this has been set, files ending with .mjs will be able to be loaded as ES Modules.

reference: https://nodejs.org/api/esm.html

Update:

Looks like you haven't export the method yet.

Suppose i have hello.mjs with content

export function sayHello() {
    console.log('hello')
}

i can use it in index.mjs like this

import {sayHello} from './hello.mjs'
sayHello()

Answer 3

If lodash had been written as modules, and lodash/index.mjs exported throttle: export const throttle = ...;, then you'd be able to import { throttle } from lodash;

The problem here is that in commonjs there's no such thing as a named export. Which means that in commonjs modules export one thing only.

So think that lodash exports an object containing a property named throttle.

For the second part of the question, I believe people will slowly start adopting ES Modules once it's not experimental anymore. At the time of this writing, it still is (Node.js v11.14).

Answer 4

For me loading lodash as ES Library did the job, here is the NPM Package for the same.

The Lodash library exported as ES modules. https://www.npmjs.com/package/lodash-es

Then you can import utils in normal way.

import { shuffle } from 'lodash-es';