Metro Bundler
ELI5 — The Vibe Check
Metro is React Native's module bundler — it takes all your JavaScript files, smooshes them together, and serves them to your app. Think of it as Webpack's mobile cousin who specializes in fast incremental builds.
Real Talk
The default JavaScript bundler for React Native that handles module resolution, transformation (via Babel), and bundling. Metro is optimized for fast incremental builds and hot module replacement in development, and produces optimized bundles for production. It watches files and re-bundles only what changed.
When You'll Hear This
"Metro's incremental builds are fast — you save a file and see the change in under a second." / "Clear Metro's cache with --reset-cache when you get weird module resolution errors."
Related Terms
Babel
Babel is the universal translator for JavaScript.
Hot Module Replacement (HMR)
HMR is the magic that makes your browser update instantly when you save a file — without refreshing the whole page and losing your app state.
React Native
React Native lets you build iPhone and Android apps using React and JavaScript. It's like React put on a disguise and snuck into the App Store.
Webpack
Webpack is the OG bundler — the grumpy grandpa of the JavaScript build world.