"CommonJS or AMD" warnings

[MickL]

Question: Is it normal to have warnings like ...js depends on 'date-fns/...'. CommonJS or AMD dependencies can cause optimization bailouts. and is the supposed way to fix it to add date-fns to allowedCommonJsDependencies? If so, doesnt it make sense to add the instruction to the readme?

Also is there an open issue on date-fns project to build ecmascript modules?

[joanllenas]

It shouldn't be normal, date-fns provides ESM builds since v2.0.0.
https://date-fns.org/v2.0.0/docs/ECMAScript-Modules

[MickL]

If they do, I wonder why the compiler complains

[joanllenas]

Ok, I've investigated a little bit more and it looks like imports need to have esm in their paths to get rid of those warnings. Like this: import addBusinessDays from 'date-fns/esm/addBusinessDays';
This is weird because the docs don't tell anything about it.

Anyway, I'm not sure if fixing esm will break ie11 applications, I will have to investigate a little more before releasing anything.

If you want to help try installing 8.0.1-beta.0 and let me know if you still see those warnings. If you have the chance to test on ie11 that would be great as well. I don't have a windows machine right now.

Cheers!

[MickL]

So i investigated a little bit into this and it seems like this is an issue of date-fns. Using 2.16.1 there is no warning and tree shaking works. Using >2.16.1 <= 2.19.0 there is a warning and FULL date-fns is imported.

So the warning is nice and correct and should not be ignored / suppressed by use of allowedCommonJsDependencies

Issue: date-fns/date-fns#2207

[joanllenas]

That's good to know, thanks for taking the time to research this.
Cheers!

[jpduckwo]

date-fns/date-fns#2339
I think this will solve this issue in future builds once merged... maybe this should be left open until date-fns is resolved and it's confirmed working?

[joanllenas]

Thanks for pointing that out @jpduckwo , I will keep an eye on that PR.
And you are right, let's keep this opened for visibility until this is fixed.

Cheers!

[joanllenas]

FYI, a new version just came out that fixes the issue:
https://github.com/date-fns/date-fns/releases/tag/v2.20.3
I will give this a try during the weekend and if it works, will update the README explaining the proper lib. ranges and so on.

[joanllenas]

Tree shaking is fixed from date-fns v2.21.1 onwards.
Just updated the README clarifying that.
Thanks for your help,
cheers!