tree shaking and "sideEffects": false ?

[macrozone]

i use uniforms on https://github.com/react-page/react-page to generate forms and i wanted to re-export the bundled uniforms version (using something like export * from 'uniforms-material').

i noticed that this will bundle everything in, even if you don't use any of the re-exports.

I think this is because uniform packages do not declare "sideEffects": false, see https://webpack.js.org/guides/tree-shaking/

i think its quite safe to set that, altough there might actually be some sideeffects (i remember that uniforms extended simpl-schema automatically in some versions, that would be a side effect. not sure if its still the case).

[radekmie]

Hi @macrozone. Yes, none of the packages actually declare sideEffects: false. I also thought about it some time ago, and, as you said, it'd be fine for most packages. There are three exceptions:

• uniforms-bridge-simple-schema and uniforms-bridge-simple-schema-2 use filterDOMProps.register to register their options. There's no need for tree shaking of this package though, as these consist basically two files - the bridge itself and this props registration (our side effects),
• uniforms-antd do the same, to simplify other fields in the theme.

The only problem is that I think that almost none of the projects would benefit from that. The majority of projects use AutoForm which will include all other components. At most, one could eliminate AutoForm and one or two components (e.g. AutoFields). Do you think it's worth to do that, having in mind potential problems?

[macrozone]

@radekmie the problem that i had is that

if my library A re-exports library B,
any consumer that include something from A will have B automatically fully bundled, even if no re-export of B is used by the consumer, because the bundler cannot tree-shake B away as it might contain side effects.

My workaround was to not re-export uniforms-material directly, but to only export the Components that i needed as exports as lazy-load components (using something like @loadable/component

i think its worth for the different edge cases.

E.g. consider a project using nextjs, where some pages use uniforms and some don't. Maybe in some pages you just import some types (without the special import type) or helper functions. these pages will have the full uniforms bundled into even if they just use some part of it.

On a side note, i think tree shaking allows libraries to use more complex libraries without declaring them as peer-dependencies (i think peer dependencies are often bad)

[mariusrak]

This change introduced a bug as I am getting error

Invalid definition for name field: "uniforms" is not a supported property

After downgrade to 3.1.0 it work correctly. I am using webpack, babel and babel preset-env to build app.