The React Native glossary

Bridgeless

The New Architecture runtime mode where the bridge is never instantiated: everything goes through JSI, Turbo Modules, and Fabric.

Codegen

React Native’s build-time tool that generates the native glue (C++, Java, Objective-C++) from TypeScript or Flow spec files.

Fabric

The New Architecture renderer: a C++ core shared by iOS and Android that computes layout synchronously.

JSI (JavaScript Interface)

The C++ API that lets JavaScript hold direct references to native objects with no serialization: the foundation of the New Architecture.

New Architecture

The rewrite of React Native internals (Fabric, Turbo Modules, JSI), on by default since 0.76 and the only architecture since 0.82.

Turbo Modules

Native modules in the New Architecture: a TypeScript spec, code generated by Codegen, and lazy loading through JSI.

Config plugin

A JavaScript function declared in app.json that modifies the native projects prebuild generates (Info.plist, manifest, Gradle, Podfile).

Development build

A debug build of your own app that includes expo-dev-client: your native modules, plus a launcher to connect to Metro.

Expo

The open-source framework React Native recommends: a native module SDK, a CLI, prebuild, Expo Router, and the EAS cloud services.

Expo Go

Expo’s sandbox app, with a fixed set of native modules: for learning and prototyping, not for shipping.

Fast Refresh

React Native’s hot reloading: a component edit is applied within a second or two while local state is preserved.

Metro

React Native’s JavaScript bundler: it resolves, transforms, and serializes your code into a bundle, and runs the dev server.

Monorepo

One repository holding several packages linked by the package manager (workspaces); needs care around Metro, autolinking, and dependency hoisting.

Prebuild (Continuous Native Generation)

The Expo command that generates the android and ios folders from app.json and config plugins instead of maintaining them by hand.

React Native DevTools

React Native’s built-in debugger since 0.76, based on Chrome DevTools: console, breakpoints, network, profiling, React tree.

Autolinking

The mechanism that discovers native libraries in node_modules and adds them to the Podfile and Gradle with no manual edits.

CocoaPods

React Native’s historical iOS dependency manager (Podfile, pod install, .xcworkspace), in maintenance mode and being replaced by SwiftPM.

Expo Modules API

Expo’s API for writing native modules and views in Swift and Kotlin with one shared DSL, with no Objective-C or bridge boilerplate.

Nitro Modules

Margelo’s framework for writing native modules in Swift, Kotlin, or C++ exposed to JavaScript through JSI, with bindings generated from TypeScript.

Prebuilt (precompiled React Native)

React Native core shipped as precompiled binaries (iOS XCFrameworks, Android AARs) downloaded at build time instead of rebuilt from source.

Swift Package Manager (SwiftPM)

Swift’s official package manager, built into Xcode, which React Native is adopting to replace CocoaPods (experimental in 0.87 and 0.88).

XCFramework

Apple’s format for shipping a multi-platform binary framework (device, simulator, macOS) in one bundle; React Native ships its precompiled core in it.

EAS Build

Expo’s hosted build service: profiles in eas.json, credentials management, and macOS and Linux runners for iOS and Android.

OTA update (EAS Update)

Shipping a new JavaScript bundle and its assets to installed apps without going through the stores; EAS Update is Expo’s service for it.

Runtime version

The identifier that guarantees an OTA update is only applied to builds whose native code is compatible with it.

Cold start (startup time)

Launching the app from scratch, process included: native init, bundle load, first React render, up to a usable screen (TTI).

FlashList

Shopify’s list, a FlatList replacement: it recycles cells instead of unmounting them, and v2 no longer asks for a size estimate.

Hermes

Meta’s JavaScript engine for React Native, the default since 0.70, which precompiles the bundle to bytecode at build time.

Worklet

A small JavaScript function the Reanimated Babel plugin extracts to run on the UI thread, in a separate runtime.

Deep linking

Opening a specific screen of the app from a URL: a custom scheme (myapp://) or a verified https link (universal links, App Links).

Expo Router

Expo’s file-based router: every file in the app directory becomes a screen, with deep links and typed routes out of the box.

Gesture Handler

Software Mansion’s library that recognizes gestures (pan, tap, pinch, and more) natively and composes them, with callbacks on the UI thread.

React Navigation

The standard navigation library for React Native: stack, tabs, drawer, with native screens through react-native-screens.

Reanimated

Software Mansion’s animation library that runs animations on the UI thread through worklets, without waiting on the JavaScript thread.

Universal links and App Links

Ordinary https links that open the app when installed, proven by a file hosted on your domain (AASA, assetlinks.json).