ES Modules does not work with namespaced library

Version: 12.0.0
Platform: Windows 10

I'm using experimental-modules since v8. I tried to use "type": "module" in v12 and it's fine except for namespaced library (uuid, lodash, ...)

This kind of imports:

import uuid from 'uuid/v4'
import countBy from 'lodash/countBy'

Causes this error:

internal/modules/esm/default_resolve.js:69
  let url = moduleWrapResolve(specifier, parentURL);
            ^
Error: Cannot find module 'd:\[...]\node_modules\uuid\v4' imported from d:\[...]\[...].mjs
    at Loader.resolve [as _resolve] (internal/modules/esm/default_resolve.js:69:13)
    at Loader.resolve (internal/modules/esm/loader.js:70:33)
    at Loader.getModuleJob (internal/modules/esm/loader.js:143:40)
    at ModuleWrap.<anonymous> (internal/modules/esm/module_job.js:43:40)
    at link (internal/modules/esm/module_job.js:42:36)

the modules implementation currently disables extension resolution. you'll need to use --es-module-specifier-resolution=node to get the good behaviour or go into the lodash and uuid folders and check what the extensions of those files are and add that to the import.

Closing as answered.

@devsnek

Had this same issue, @devsnek solution worked, thanks!

@bnoordhuis

this is sort of an ongoing feedback thing for modules team so i'm gonna re-open it

cc @bnoordhuis

@aadamsx

@aadamsx how are you using lodash-es + experimental-modules flag on node?

This node --experimental-modules --experimental-json-modules --es-module-specifier-resolution=node index.js does not work for me with the following code:

//index.js
import func from './func.js';
console.log(func(1, 1.2));

// func.js
import { round } from 'lodash-es';
console.log(round);
export default (a, b) => round(a + b);

Error =>

file:///Users/damiano/Desktop/node-jest/func.js:1
import { round } from 'lodash-es';
         ^^^^^
SyntaxError: The requested module 'lodash-es' does not provide an export named 'round'
    at ModuleJob._instantiate (internal/modules/esm/module_job.js:93:21)
    at async ModuleJob.run (internal/modules/esm/module_job.js:108:20)
    at async Loader.import (internal/modules/esm/loader.js:128:24)
error Command failed with exit code 1.

Regarding

Currently only the “default export” is supported for CommonJS files or packages

Is node or the modules loader able to see that the file is exported via module.exports? If so, would it not be possible to export the hole object as default and every object entry as named export?
eg.

commonjs.js

  module.exports = {
    a: 1,
    b: 2,
    c: 3,
  }

node12.js:

  import abc, { a as foobar } from './commonjs.js'
  abc.a === 1 && foobar === 1 && console.log('Yippi')

no, we have to declare the export names before evaluation, so we don't know what module.exports looks like.

Have the same issue. And then when I use --es-module-specifier-resolution=node it breaks CommonJS modules in the namespaced library project SyntaxError: The requested module 'date-fns' does not provide an export named 'format'

Have the same issue. And then when I use --es-module-specifier-resolution=node it breaks CommonJS modules in the namespaced library project SyntaxError: The requested module 'date-fns' does not provide an export named 'format'

Have same issue with date-fns. Try using this syntax, works for me:
import format from 'date-fns/format'

@ench0

@ench0 @TrevTheDev be careful: import format from 'date-fns/format' works only because the format.js file is not importing other files, otherwise death ☠️.

Try to import a lodash-es/whatever, or also a date-fns/whatever which imports other modules in the same library.

@ench0

@ench0 @TrevTheDev be careful: import format from 'date-fns/format' works only because the format.js file is not importing other files, otherwise death ☠️.

Try to import a lodash-es/whatever, or also a date-fns/whatever which imports other modules in the same library.

Tried, this is my full list of imports, no issues at all:

// @ts-ignore
import toDate from 'date-fns/toDate'
import addDays from 'date-fns/addDays'
import addHours from 'date-fns/addHours'
import addMinutes from 'date-fns/addMinutes'
import getYear from 'date-fns/getYear'
import getMonth from 'date-fns/getMonth'
import getDate from 'date-fns/getDate'
import startOfDay from 'date-fns/startOfDay'
import endOfDay from 'date-fns/endOfDay'
import isBefore from 'date-fns/isBefore'
import isAfter from 'date-fns/isAfter'
import isWithinInterval from 'date-fns/isWithinInterval'
import differenceInSeconds from 'date-fns/differenceInSeconds'

@guybedford

@guybedford I understand, but what is the intended path for all the ecosystem to move to ESM then?
Do you expect all package mantainers to add the exports field in the package.json?

As a package consumer, just including extensions for any resolution not governed by main or exports. And this will ensure compatibility in other JS environments too.

…

On Sat, Apr 11, 2020 at 00:23 Damiano ***@***.***> wrote: @guybedford <https://github.com/guybedford> I understand, but what is the intended path for all the ecosystem to move to ESM then? Do you expect all package mantainers to add the exports field in the package.json? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#27408 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAESFSX7V2VUDL65FJC5R3DRMALF5ANCNFSM4HILSXPQ> .

@guybedford

@guybedford I'm not sure I understood, my bad!
Do you know a library who is handling both esm and cjs correctly at the moment so I can get an idea on how to move?

@damianobarbati

@damianobarbati in https://unpkg.com/browse/es-get-iterator@1.1.0/, i'm using the exports field combined with main to load index.js as CJS and in browsers, node.js in CJS node, and node.mjs in ESM node. I'm also allowing ./package.json and ./package (which only works for require atm, but would work for import in the future if JSON ESM became a thing)

@ljharb

@ljharb thank you! I'll give it a try soon.

Link to node --experimental-specifier-resolution

Add exports within package.json to enable scoped package loading.

feat(esm): Add exports within package.json to enable scoped package l…

feat(esm): Add test case for esm imports.

feat(esm): Add exports within package.json to enable scoped package l…

Use `--es-module-specifier-resolution=node`

Esm fixes (#34)

Changed imports to include index as specified in nodejs/node#27408 (c…

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ES Modules does not work with namespaced library #27408

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ES Modules does not work with namespaced library #27408

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devsnek commented on Apr 25, 2019

bnoordhuis commented on Apr 28, 2019

aadamsx commented on May 5, 2019

devsnek commented on May 5, 2019

damianobarbati commented on May 23, 2019

valoricDe commented on Sep 18, 2019

devsnek commented on Sep 18, 2019

TrevTheDev commented on Dec 14, 2019

ench0 commented on Mar 9, 2020

damianobarbati commented on Mar 9, 2020

ench0 commented on Mar 10, 2020

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damianobarbati commented on Apr 11, 2020

guybedford commented on Apr 11, 2020

damianobarbati commented on Apr 15, 2020

ljharb commented on Apr 15, 2020

damianobarbati commented on Apr 15, 2020

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