Packager over-eagerly optimises require values

[notjosh]

Description

I'm trying to use decimal.js, which works fine in development. But when running the packager in production mode, it fails with:

Unable to resolve module crypto [/path/to]/node_modules/decimal.js/decimal.js: Module does not exist in the module map or in these directories:
[/path/to]/node_modules

Reproduction

npm install decimal.js
react-native bundle --dev=false --platform=ios --entry-file=index.ios.js --bundle-output dist/Something.jsbundle --sourcemap-output dist/Something.jsbundle.map --assets-dest dist

Additional Information

decimal.js uses a relatively naive packager-buster, but RN is is folding the constants.

As there's no standard way to omit requires from packagers (that I'm aware of), I've submitted a PR on their side (MikeMcl/decimal.js#42) to thwart the RN packager - but that's a game of cat-and-mouse.

Ideally there'd be an annotation (/* packager-ignore */ or similar) to prevent this from happening.

As this kind of thing exists in other npm modules also, would it make sense to perhaps remove folding of the constants?

• React Native version: 0.35.0
• Platform: iOS
• Operating System: macOS

[jonrh]

Just had this issue myself by having math.js v3.9.2 as a dependency (which relies on decimal.js v5.0.8). Decimal.js has released a fix which makes it compatible with React Native (v7.0.0 and newer).

I created a sample React Native project which demonstrates this issue: https://github.com/jonrh/react-native-mathjs-bug. I've created an issue in the math.js library asking if it would be possible for them to upgrade their decimal.js dependency, that might solve the problem short-term.

[ide]

The packager mandates that all requires are statically available, perhaps that could change in the future (cc @cpojer). In the meantime you could write a custom Babel plugin that removes the requires.

[jonrh]

Thanks for the insights @ide, wasn't aware that was the case. As to my own case this issue has been solved with v3.9.2 in math.js thanks to the swift response of the maintainers. Thank you all for your brilliant work in the React Native repo!

[hramos]

Hi there! This issue is being closed because it has been inactive for a while. Maybe the issue has been fixed in a recent release, or perhaps it is not affecting a lot of people. Either way, we're automatically closing issues after a period of inactivity. Please do not take it personally!

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