feat: add CJS build output for dual format #518
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
mtqperson
force-pushed
the
mtq/add-cjs
branch
from
c0e1008 to
2d299ba
Compare
NiklasRamstrom
approved these changes
Nov 24, 2025
Contributor
NiklasRamstrom
left a comment
NiklasRamstrom
left a comment
There was a problem hiding this comment.
Looks good to me, with my limited knowledge of ESM vs CJS :)
Did a quick test locally from the theme-package on the branch and did not see any problems using the ESM part.
mtqperson
force-pushed
the
mtq/add-cjs
branch
from
2d299ba to
78cc526
Compare
Ideally we want to use ESM, but the reality is that @fluentui/react-theme (and other Fluent packages) ESM lacks Node.js compliance (missing .js extensions) - it works in bundlers but not in Node.js. This means downstream tools are forced to use a CJS bundler, which can `require` Fluent UI from `node_modules` because Fluent has CJS exports as a fallback. However, this package doesn't provide CJS, so such a downstream bundler cannot `require` it and must bundle our source into its own dist instead. By adding CJS here, downstream libraries can externalize us from node_modules, reducing their bundle sizes. Otherwise we become a nested dependency. - Add build:cjs script and lib-commonjs output - Update exports with require condition - Remove "type": "module" for dual-format semantics
mtqperson
force-pushed
the
mtq/add-cjs
branch
from
78cc526 to
e7bccbd
Compare
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Ideally we want to use ESM, but the reality is that @fluentui/react-theme (and other Fluent packages) ESM lacks Node.js compliance (missing .js extensions) - it works in bundlers but not in Node.js.
This means downstream tools are forced to use a CJS bundler, which can
requireFluent UI fromnode_modulesbecause Fluent has CJS exports as a fallback.However, this package doesn't provide CJS, so such a downstream bundler cannot
requireit and must bundle our source into its own dist instead.By adding CJS here, downstream libraries can externalize us from node_modules, reducing their bundle sizes. Otherwise we become a nested dependency.