Babel plugin

@parallax-rn/babel-plugin is the build-time part of Parallax. In development builds it writes, for every file with JSX, a table of its elements: where each is used, which component it is in, what it was imported from and the testID you wrote. It registers the table in the running app, so a tool can map what is on screen to a file and line.

It never changes the code you wrote; it appends one statement. It has no third-party runtime dependencies.

InstallCopy Anchor Link

1. In the app's project root, add the package: npm i -D @parallax-rn/babel-plugin@0.1.0-beta.2, or your package manager's equivalent. Use the same version as the MCP server.

2. List the plugin in your Babel config, before react-native-worklets/plugin if you use it (that plugin must be last):

   Copy Text

   // babel.config.js
   module.exports = {
     presets: ['module:@react-native/babel-preset'],
     plugins: ['@parallax-rn/babel-plugin', 'react-native-worklets/plugin'],
   };

3. Restart Metro with --reset-cache: npx react-native start --reset-cache (bare React Native) or npx expo start -c (Expo). Metro's transform cache does not notice a change of babel.config.js or of the plugin.

4. Run npx -y @parallax-rn/mcp@0.1.0-beta.2 doctor in the project root. It reads the tables from the running app.

UpdateCopy Anchor Link

Update the package, then restart Metro with --reset-cache. Until the cache is reset, tables written by the older version stay in the bundle and point to wrong files and lines. Every table carries the plugin version, and doctor and status warn "source tables are stale" when it differs from the installed one.

OptionsCopy Anchor Link

['@parallax-rn/babel-plugin', { injectTestIDs: false, root: process.cwd(), exclude: ['/stories/'] }]

Unknown options are an error. Files with no JSX, files in node_modules, generated files (marked @generated or codegen in the first three comments) and files outside root get no table.

Development onlyCopy Anchor Link

• The plugin is active only when Babel's environment is development. Otherwise the output is what it would be without the plugin.
• It is a build error when Babel's environment is development but NODE_ENV is production (a release pipeline told to build a development bundle). The error says to build releases with dev=false.
• The emitted code is guarded by __DEV__.
• There is no option to force the plugin on in a release build.

Check a release bundle in CICopy Anchor Link

parallax-bundle-check searches a release bundle, or the Hermes bytecode made from it, for what the plugin and the SDK leave behind: __PARALLAX_RN__, __PARALLAX_RN_PUSH__ and injected prn:…::n ids.

npx parallax-bundle-check ios/build/main.jsbundle

Add --json for machine-readable output. Exit code 0 means clean, 1 means something was found (listed with counts), 2 means a usage or file error.