`dayjs` does not actually support Node.js ESM #1765

CyanSalt · 2022-01-13T13:03:33Z

Node.js has implemented native support for ESM in the real world, and the community is increasingly recommending the use of ESM instead of CommonJS (e.g: https://blog.sindresorhus.com/get-ready-for-esm-aa53530b3f77).

I noticed that dayjs actually publishes the esm directory, which contains the compiled product of the ESM syntax, see #1298. Although the "module" field of package.json was removed in #1314, the contents of esm are actually still available in the <script type="module"> in browsers or in bundling tools such as webpack.

Unfortunately, Node.js requires more than that for ESM. Since this is a CommonJS package, the ESM files it provides must use the .mjs extension to be properly parsed by Node.js.

I can get a few ways to solve this problem, but perhaps none of them are very good:

The easiest way to make it work is to replace the .js extension with .mjs in build/esm.js, but obviously this will cause breaking changes for scenarios that already use ESM files.
We can also publish a new node-esm directory for .mjs files for Node.js. But node-esm is not a good name for forward compatibility reasons.
Further, as described in fix: remove module entry in package.json #1314, continue to push the implementation of the dayjs-esm package, just like lodash-es.
- If we take this approach, we also no longer need to use the .mjs extension. Just keep using .js.

I'm not sure if you have plans for this in terms of Node.js ESM, but I think that this is the way to go.

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katerlouis · 2022-03-16T15:59:39Z

Any news here?

benmccann · 2022-05-04T03:40:51Z

2.0 supports ESM

steffanhalv · 2022-08-05T09:42:56Z

2.0 supports ESM

import dayjs from 'https://cdn.jsdelivr.net/npm/dayjs@2.0.0-alpha.2/dist/index.mjs'
console.log(dayjs()) // It works 👍🏼

michaelhays · 2023-03-20T18:48:50Z

Looks like the 2.0 alpha may be abandoned -- no new commits or releases in 6 months.

Is there a plan to re-open work on 2.0, or to bring ESM support to 1.0?

neilsoult · 2023-05-24T14:58:24Z

Looks like the 2.0 alpha may be abandoned -- no new commits or releases in 6 months.

Is there a plan to re-open work on 2.0, or to bring ESM support to 1.0?

BUMP

MonsterDeveloper · 2023-08-29T16:28:38Z

Any ETA on ESM arrival on NPM?

DaniilIsupov · 2023-09-13T13:35:23Z

I'm also waiting for Node.js ESM support

Lauro235 · 2023-09-29T13:30:53Z

Would be great to get ESM support!

andyg3 · 2023-09-29T14:36:16Z

Another vote here for ESM support.

n3ih7 · 2023-10-05T16:38:27Z

Come on! Where is ESM support?

## Summary Adding `dayjs` to `opensource`, as it's needed by the translation framework. ## Test plan Place `experimental.PagePresence` on the testbed, hover on avatar of users who haven't been present in a long time, check the tooltip has the right subtitle ## Old summary, before Josh moved us to ESM This is the second attempt at this. The first one was reverted (#7592) because it crashed at runtime. The original PR (#7473) had some `@ts-ignore` and was using `require`, which is why the build succeeded even though it should have not. `import * as dayjs from 'dayjs';` is a valid import according to `tsc`. But then `dayjs(date)` errors ``` Type originates at this import. A namespace-style import cannot be called or constructed, and will cause a failure at runtime. Consider using a default import or import require here instead ``` It also **crashes at runtime**. Changing it to `dayjs.default(date)` doesn't crash at runtime, but `tsc` now complains about it ``` Property 'default' does not exist on type 'typeof import("/Users/albert/monorepo/opensource/sdk-js/node_modules/dayjs/index.d.ts")' ``` `import dayjs from 'dayjs';` is **not** a valid import according to `tsc` ``` This module is declared with 'export =', and can only be used with a default import when using the 'esModuleInterop' flag. ``` But **actually works** (i.e. no runtime crash). Peeking into `dayjs` codebase, I see an [export default dayjs](https://github.com/iamkun/dayjs/blob/f0c9a41c6ec91528f3790e442b0c5dff15a4e640/src/index.js#L467C21-L467C21), which is ESM syntax, which I would expect to just be able to import (`import dayjs from 'dayjs';`). My IDE is not complaining, the code is not crashing at runtime, but `npm run tsc-once` is yelling at me. [There is a long-standing issue in DayJS regarding Node.js ESM](iamkun/dayjs#1765)) which might be related. But I'm still confused 😬 Test Plan: Use the experimental.PresenceFacepile in the testbed, hover on an avatar, check the tooltip's subtitle is correct. Reviewers: Netceer, lazybean Reviewed By: lazybean Pull Request: getcord/monorepo#7750 monorepo-commit: 9ea55f11df0954eff1e344bcf12c1f9c2a474541

0x80 · 2024-02-10T21:28:58Z

Damn I just wasted hours on this 🤦‍♂️ When converting a large codebase to a monorepo, I kept getting errors like this at runtime:

Error [ERR_MODULE_NOT_FOUND]: Cannot find module '/Users/me/myproject/
services/fns/node_modules/dayjs/plugin/advancedFormat' imported from /Users/me/myproject/services/fns/dist/index.js
Did you mean to import dayjs@1.11.10/node_modules/dayjs/plugin/advancedFormat.js?

I couldn't figure it out because my bundled shared packages output looked correct, but I assumed it must be a mistake in some configuration. I tried everything I could think of before landing here.

I did not imagine a popular library like this would not have support for ESM yet in 2024.

I'll give the alpha 2.0 a try. Also found this issue describing that it should work by adding the .js import. It is unexpected, because extension prefixes are only required on ESM imports from relative paths, and never from an external library, but that must be a side effect of the funky not-really-esm exports.

0x80 · 2024-02-10T22:18:07Z

The types in 2.0 alpha didn't seem to work for me. For example, TS didn't recognize that .utc() was available after applying the plugin. I ended up sticking .js to the v1 imports and that works for now.

blackfalcon · 2024-02-13T00:34:24Z

Running SSR build with Svelte/Vite

(node:29857) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.
(Use `node --trace-warnings ...` to show where the warning was created)
/Users/dalesande/src/personal/sveltekit-auro/node_modules/dayjs/esm/index.js:1
import * as C from './constant';

Not sure if this is the fix you want, but I simply updated all the JS references to be .mjs and that fixed it. I pushed up a branch of the changes. The tests don't work, but thought this would be easy to see the diff.

dev...blackfalcon:dayjs:dev

alex-arriaga · 2024-02-19T22:55:02Z

Another vote here for ESM support.

codyfrisch · 2024-03-05T20:53:17Z

Two years on and nothing on proper ESM support tells me this is a dead end project and I need to migrate my code to another library. ESM is the only way forward, that is written on the wall.

michaelhays · 2024-03-05T20:58:13Z

Two years on and nothing on proper ESM support tells me this is a dead end project and I need to migrate my code to another library. ESM is the only way forward, that is written on the wall.

Pretty much, I'm just waiting patiently for https://github.com/tc39/proposal-temporal to hit Stage 4 so I can migrate my Day.js code to that 🙏

codyfrisch · 2024-03-05T21:06:19Z

Two years on and nothing on proper ESM support tells me this is a dead end project and I need to migrate my code to another library. ESM is the only way forward, that is written on the wall.

Pretty much, I'm just waiting patiently for https://github.com/tc39/proposal-temporal to hit Stage 4 so I can migrate my Day.js code to that 🙏

That would be ideal, but I have a requirement for format strings, and unfortunately I'm dealing with interop where there is an expectation for the moment.js/day.js style formatting strings. I suppose I could write something that converts between them... and use date-fns (I am assuming temporal is going to use unicode tokens like date-fns since its a standard).

blackfalcon · 2024-03-07T03:12:52Z

Two years on and nothing on proper ESM support tells me this is a dead end project and I need to migrate my code to another library. ESM is the only way forward, that is written on the wall.

The current version covers my use case, time to fork.

tangxiangmin · 2024-05-14T07:49:06Z

looks bad but work fine 🙅🏻‍♀️

Has there been any progress on this issue?

benmccann mentioned this issue May 4, 2022

🌟 Day.js 2.0 alpha preview is available #1879

Closed

Bykiev mentioned this issue Aug 18, 2022

ESM modules aren't registered in package.json #2025

Open

aloisklink mentioned this issue May 29, 2023

Release 10.2.2 mermaid-js/mermaid-live-editor#1231

Merged

3 tasks

louis-bompart mentioned this issue Jun 9, 2023

feat: add search analysis module coveo/platform-client#680

Merged

6 tasks

blackfalcon mentioned this issue Mar 10, 2024

Fork day.js to address ESM support AlaskaAirlines/auro-pane#57

Open

jamalsoueidan mentioned this issue Apr 12, 2024

Cannot read properties of undefined (reading 'extend') mantinedev/mantine#6068

Closed

2 tasks

siarheiyelin mentioned this issue Apr 18, 2024

[Dead code elimination] Improve ability of unused code to be removed by minifiers epam/UUI#2178

Open

24 tasks

YunYouJun mentioned this issue Apr 29, 2024

Migrate dayjs to date-fns YunYouJun/valaxy#388

Closed

1 task

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`dayjs` does not actually support Node.js ESM #1765

`dayjs` does not actually support Node.js ESM #1765

CyanSalt commented Jan 13, 2022 •

edited

katerlouis commented Mar 16, 2022

benmccann commented May 4, 2022

steffanhalv commented Aug 5, 2022 •

edited

michaelhays commented Mar 20, 2023

neilsoult commented May 24, 2023

MonsterDeveloper commented Aug 29, 2023

DaniilIsupov commented Sep 13, 2023

Lauro235 commented Sep 29, 2023

andyg3 commented Sep 29, 2023

n3ih7 commented Oct 5, 2023 •

edited

0x80 commented Feb 10, 2024 •

edited

0x80 commented Feb 10, 2024 •

edited

blackfalcon commented Feb 13, 2024

alex-arriaga commented Feb 19, 2024

codyfrisch commented Mar 5, 2024

michaelhays commented Mar 5, 2024

codyfrisch commented Mar 5, 2024

blackfalcon commented Mar 7, 2024

tangxiangmin commented May 14, 2024

dayjs does not actually support Node.js ESM #1765

dayjs does not actually support Node.js ESM #1765

Comments

CyanSalt commented Jan 13, 2022 • edited

katerlouis commented Mar 16, 2022

benmccann commented May 4, 2022

steffanhalv commented Aug 5, 2022 • edited

michaelhays commented Mar 20, 2023

neilsoult commented May 24, 2023

MonsterDeveloper commented Aug 29, 2023

DaniilIsupov commented Sep 13, 2023

Lauro235 commented Sep 29, 2023

andyg3 commented Sep 29, 2023

n3ih7 commented Oct 5, 2023 • edited

0x80 commented Feb 10, 2024 • edited

0x80 commented Feb 10, 2024 • edited

blackfalcon commented Feb 13, 2024

alex-arriaga commented Feb 19, 2024

codyfrisch commented Mar 5, 2024

michaelhays commented Mar 5, 2024

codyfrisch commented Mar 5, 2024

blackfalcon commented Mar 7, 2024

tangxiangmin commented May 14, 2024

`dayjs` does not actually support Node.js ESM #1765

`dayjs` does not actually support Node.js ESM #1765

CyanSalt commented Jan 13, 2022 •

edited

steffanhalv commented Aug 5, 2022 •

edited

n3ih7 commented Oct 5, 2023 •

edited

0x80 commented Feb 10, 2024 •

edited

0x80 commented Feb 10, 2024 •

edited