问题
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?
回答1:
EDITED NEW (AND MUCH BETTER) ANSWER
The Node team is ... slow. Meanwhile, the same guy who brought us Lodash (John-David Dalton) imagined a brilliant solution, and his idea is the best way to get full ES6 module support in 2019.
(In fact, I want to delete my earlier answer, but I've left it for historical purposes.)
The new solution is SUPER simple.
Step #1:
npm i esm
(https://www.npmjs.com/package/esm for package details)
Step #2:
node -r esm yourApp.js
That's the entirety of it: it's really just that easy. Just add -r esm as a Node arg, and everything just magically works (it's even less typing than --experimental-modules!) Thank you John-David Dalton!!!
As I said in my original answer, presumably someday Node will finally release full ES6 support, but when that happens adopting it will be as easy as removing "-r esm" from a few scripts :D
Finally, to give credit where due, while I didn't find it through his answer, @Divyanshu Rawat actually provided an answer with the precursor to this library long before I made this update.
ORIGINAL ANSWER
--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.
回答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()
回答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).
回答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';
来源：https://stackoverflow.com/questions/47277887/node-experimental-modules-requested-module-does-not-provide-an-export-named