@react-native/metro-config
Metro configuration for React Native.
About
Metro configuration for React Native.
Live mirror of the GitHub README. Updated whenever the repo's default branch changes.
@react-native/metro-config
Installation
yarn add --dev @react-native/js-polyfills metro-config @react-native/metro-babel-transformer metro-runtime @react-native/metro-config
Note: We're using yarn to install deps. Feel free to change commands to use npm 3+ and npx if you like
Testing
To run the tests in this package, run the following commands from the React Native root folder:
yarnto install the dependencies. You just need to run this onceyarn jest packages/metro-config.
Quick facts
npm install @react-native/metro-configHow Sourcemap Explorer detects @react-native/metro-config
We catch @react-native/metro-config from two complementary signals: bundled source paths and the embedded package.json. Modern bundlers (webpack, Vite, esbuild, Rollup, Turbopack) preserve the original node_modules/@react-native/metro-config/ paths inside the JavaScript sourcemap's sources[] array — that's the canonical signal. When the matching package.json is also captured in sourcesContent[], we read the exact version field — patch number included. No regex guessing, no version inference.
- 1
Confirm the site exposes sourcemaps
In DevTools Network, check the response headers of any application script for `SourceMap` or `X-SourceMap`. Failing that, fetch the script's last 4 KB and look for a `//# sourceMappingURL=` comment.
- 2
Find the package in the bundle
Open DevTools → Network → reload. Click any application script and look at its sourcemap. Inside, search `sources[]` for entries matching `node_modules/@react-native/metro-config/` — every match confirms the package is bundled. The matching `sourcesContent[i]` for `node_modules/@react-native/metro-config/package.json` gives you the exact installed version.
- 3
Read the version directly from package.json
Run `jq -r '. as $m | $m.sources | to_entries[] | select(.value | endswith("node_modules/@react-native/metro-config/package.json")) | $m.sourcesContent[.key] | fromjson | .version' bundle.js.map`. Sourcemap Explorer automates the same query in the popup.
Recent versions
FAQ
What is @react-native/metro-config used for?
Metro configuration for React Native.
How can I tell if a website is using @react-native/metro-config?
Open the page in Chrome with the Sourcemap Explorer extension installed and read the Stack tab. We catch `@react-native/metro-config` from two complementary signals: `node_modules/@react-native/metro-config/` paths inside the JavaScript sourcemap, and the embedded `package.json` we read for exact-version detection. Without the extension you can do the same lookup manually in DevTools — the steps are listed in the "How Sourcemap Explorer detects" section above.
What is the latest version of @react-native/metro-config?
0.85.3, as published on the npm registry. The "Recent versions" table on this page lists the most recent 8 releases with their release dates. Sourcemap Explorer reports the version actually bundled into a site, which can lag the latest release by months on real-world deployments.
Where can I read more?
Project homepage: https://github.com/facebook/react-native/tree/HEAD/packages/metro-config#readme. Source code: https://github.com/facebook/react-native. Published on npm: https://www.npmjs.com/package/@react-native/metro-config. Licensed as MIT.
Detected by Sourcemap Explorer
When a bundle ships sourcemaps, we read the embedded package.json for @react-native/metro-config and report the precise version. Without sourcemaps, an import / require in the page's scripts is enough to flag it.