@react-native/babel-preset imports from react-native not deferred (lazy requires)
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Description
Description
The expected behaviour of @react-native/babel-preset is to defer the evaluation of a subset of react-native modules until the scope in which they are first referenced: https://github.com/facebook/react-native/blob/main/packages/react-native-babel-preset/src/configs/main.js#L76
This is no longer happening (as @babel/plugin-transform-modules-commonjs passes the source string to the lazy callback, not the expected import specifier). See test 2.
Steps to reproduce
git clone git@github.com:stevoland/RNTest.git
git checkout lazy-imports-repro
yarn
yarn test babel.test
React Native Version
0.73.4
Affected Platforms
Runtime - Android, Runtime - iOS
Output of npx react-native info
System:
OS: macOS 14.1
CPU: (12) arm64 Apple M2 Pro
Memory: 898.08 MB / 32.00 GB
Shell:
version: 3.2.57
path: /bin/bash
Binaries:
Node:
version: 18.18.0
path: ~/.nvm/versions/node/v18.18.0/bin/node
Yarn:
version: 1.22.19
path: ~/.nvm/versions/node/v18.18.0/bin/yarn
npm:
version: 9.8.1
path: ~/.nvm/versions/node/v18.18.0/bin/npm
Watchman:
version: 2024.04.15.00
path: /opt/homebrew/bin/watchman
Managers:
CocoaPods:
version: 1.11.3
path: /usr/local/bin/pod
SDKs:
iOS SDK:
Platforms:
- DriverKit 23.0
- iOS 17.0
- macOS 14.0
- tvOS 17.0
- watchOS 10.0
Android SDK: Not Found
IDEs:
Android Studio: 2021.1 AI-211.7628.21.2111.8309675
Xcode:
version: 15.0/15A240d
path: /usr/bin/xcodebuild
Languages:
Java:
version: 21.0.3
path: /Users/stephen.collings/.sdkman/candidates/java/current/bin/javac
Ruby:
version: 2.6.10
path: /usr/bin/ruby
npmPackages:
"@react-native-community/cli": Not Found
react:
installed: 18.2.0
wanted: 18.2.0
react-native:
installed: 0.73.4
wanted: 0.73.4
react-native-macos: Not Found
npmGlobalPackages:
"*react-native*": Not Found
Android:
hermesEnabled: true
newArchEnabled: false
iOS:
hermesEnabled: Not found
newArchEnabled: false
Stacktrace or Logs
FAIL __tests__/lazy-imports.test.ts
✕ should defer select react-native imports (403 ms)
✓ should defer all imports (26 ms)
● should defer select react-native imports
expect(received).toMatchInlineSnapshot(snapshot)
Snapshot name: `should defer select react-native imports 1`
- Snapshot - 1
+ Received + 1
- "function _reactNative(){var data=require("react-native");_reactNative=function _reactNative(){return data;};return data;}var a=function a(){return _reactNative().AccessibilityInfo;};"
+ "var _reactNative=require("react-native");var a=function a(){return _reactNative.AccessibilityInfo;};"
17 | const a = () => AccessibilityInfo`;
18 |
> 19 | expect(transform(input)).toMatchInlineSnapshot(
| ^
20 | `"function _reactNative(){var data=require("react-native");_reactNative=function _reactNative(){return data;};return data;}var a=function a(){return _reactNative().AccessibilityInfo;};"`,
21 | );
22 | });
at Object.toMatchInlineSnapshot (__tests__/lazy-imports.test.ts:19:28)
Reproducer
https://github.com/stevoland/RNTest/commit/02effcb07917e94cd2d5a87670a69d6c0e627fc1
Screenshots and Videos
No response
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
The behavior is covered by tests/lazy-imports.test.ts and the preset's lazy-import configuration in packages/react-native-babel-preset/src/configs/main.js. Start by running the reproduction commands and inspect how the Babel CommonJS transform supplies the lazy callback; done means the select-import snapshot again shows deferred evaluation and the test passes.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- react-native, typescript
- Domain
- build-system, mobile
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100