Turbo Native Modules con JSI
Definisca un file spec TypeScript per un Turbo Native Module, lo implementi in Kotlin e Swift utilizzando l'interfaccia generata da codegen e chiami il modulo in modo sincrono tramite JSI.
Turbo Native Modules con JSI è una lezione React Native Academy gratuita su CoddyKit. Questa è la lezione 3 di 4. Puoi leggere la lezione completa qui gratuitamente — poi esercitati direttamente nel browser con un editor di codice integrato e un tutor IA disponibile 24/7. Fa parte del percorso di apprendimento React Native Academy, e i tuoi progressi si sincronizzano tra il web e l'app CoddyKit. Il corso React Native Academy include 4 lezioni in totale.
Parti di questa lezione non sono ancora state tradotte e vengono mostrate in inglese.
The Problem with the Legacy Bridge
The legacy React Native bridge serializes every message between JavaScript and native into JSON, then deserializes it on the other side. This round-trip adds latency for every native call and blocks threads while serialization happens. For frequent calls like scroll events or animations, this overhead causes frame drops. JSI (JavaScript Interface) was created to eliminate this bottleneck.
What Is JSI
JSI (JavaScript Interface) is a lightweight C++ layer that lets JavaScript hold direct references to C++ host objects. Instead of sending a JSON-serialized message across the bridge, a JS call invokes a C++ function pointer directly and synchronously. This means native calls can be synchronous, zero-copy, and orders of magnitude faster than bridge-based calls.
Turbo Modules Architecture Overview
Turbo Native Modules are the new module system built on JSI. Key differences from legacy modules include: lazy loading (modules initialize only when first accessed instead of all at startup), typed interfaces (generated from a TypeScript spec so types are guaranteed on both sides), and synchronous calls possible without blocking the JS thread via JSI. The codegen tool generates the boilerplate C++ and native glue code automatically.
Writing the TypeScript Spec File
A Turbo Module starts with a TypeScript spec file that declares the module's interface. This file lives in your project and is processed by react-native-codegen to generate native interface files. The spec must import TurboModuleRegistry and define a type that extends TurboModule.
// NativeDeviceInfo.ts (spec file)
import type { TurboModule } from 'react-native';
import { TurboModuleRegistry } from 'react-native';
export interface Spec extends TurboModule {
getDeviceModel(): string;
getBatteryLevel(): Promise<number>;
addListener(eventType: string): void;
removeListeners(count: number): void;
}
export default TurboModuleRegistry.getEnforcing<Spec>('DeviceInfo');Running Codegen to Generate Native Code
After writing the TypeScript spec, you run React Native Codegen to generate the native interface files. For managed Expo projects, this happens automatically during expo prebuild. For bare React Native projects, run yarn react-native codegen. Codegen outputs Swift/Kotlin interfaces and C++ glue code in the build/generated folder that your native implementation must conform to.
# Bare React Native — run codegen manually
cd android && ./gradlew generateCodegenArtifactsFromSchema
# Then check generated files
ls android/app/build/generated/source/codegen/jni/
# NativeDeviceInfoJSI-generated.cpp
# NativeDeviceInfoJSI.hImplementing the Module in Kotlin
The Kotlin implementation must extend the codegen-generated abstract class (e.g., NativeDeviceInfoSpec) and override each method declared in the spec. Because the signatures are generated from TypeScript, there is no type mismatch between JS and native — the codegen enforces them at build time rather than at runtime.
// DeviceInfoModule.kt
package com.yourapp
import com.facebook.react.bridge.ReactApplicationContext
import com.yourapp.NativeDeviceInfoSpec
class DeviceInfoModule(context: ReactApplicationContext) :
NativeDeviceInfoSpec(context) {
companion object {
const val NAME = 'DeviceInfo'
}
override fun getName(): String = NAME
override fun getDeviceModel(): String {
return android.os.Build.MODEL
}
}Implementing the Module in Swift
The Swift implementation conforms to the codegen-generated protocol (e.g., NativeDeviceInfoSpec). Unlike legacy modules, there is no separate bridge .m file needed for Turbo Modules — the JSI layer handles the binding automatically once the module is registered. The protocol guarantees that the Swift method signatures match the TypeScript spec exactly.
// DeviceInfoModule.swift
import Foundation
@objc(DeviceInfoModule)
class DeviceInfoModule: NSObject, NativeDeviceInfoSpec {
func getDeviceModel() -> String {
return UIDevice.current.model
}
func getBatteryLevel(
_ resolve: @escaping RCTPromiseResolveBlock,
reject: @escaping RCTPromiseRejectBlock
) {
UIDevice.current.isBatteryMonitoringEnabled = true
resolve(UIDevice.current.batteryLevel * 100)
}
}Synchronous Calls via JSI
One of the biggest JSI benefits is the ability to call native synchronously from JS. When a Turbo Module method returns a non-Promise type (like string or number in the spec), JSI can return the value immediately without scheduling an async callback. This unlocks patterns like reading cached values synchronously that were impossible with the legacy bridge.
// TypeScript spec — synchronous return type
export interface Spec extends TurboModule {
getDeviceModel(): string; // synchronous
getBatteryLevel(): Promise<number>; // still async
}
// Usage in JS — getDeviceModel() is synchronous
import NativeDeviceInfo from './NativeDeviceInfo';
const model = NativeDeviceInfo.getDeviceModel(); // no await needed
console.log('Model:', model);Enabling the New Architecture
Turbo Modules require the New Architecture to be enabled in your project. For Android, set newArchEnabled=true in android/gradle.properties. For iOS, set RCT_NEW_ARCH_ENABLED=1 in the Podfile and run pod install. Expo SDK 50+ enables the new architecture automatically for managed workflow projects using the latest config.
# android/gradle.properties
newArchEnabled=true
# ios/Podfile — add before use_react_native!
ENV['RCT_NEW_ARCH_ENABLED'] = '1'
# Then reinstall pods
cd ios && pod installRegistering a Turbo Module
Turbo Modules are registered via a TurboModuleManagerDelegate instead of a ReactPackage. On Android you modify MainApplicationTurboModuleManagerDelegate.kt; on iOS you modify RCTAppDelegate.mm. The codegen also generates a ModuleProvider that wires up the module automatically when you follow the standard naming conventions.
// Android: MainApplicationTurboModuleManagerDelegate.kt
override fun getModule(
reactApplicationContext: ReactApplicationContext,
name: String
): NativeModule? {
return when (name) {
DeviceInfoModule.NAME -> DeviceInfoModule(reactApplicationContext)
else -> null
}
}Comparing Legacy vs Turbo Module Performance
Benchmarks show Turbo Modules can be 2–3x faster for high-frequency calls compared to legacy bridge modules. The improvement is most noticeable for calls made in rapid succession — such as gesture handlers or animation drivers. For infrequent calls like camera setup, the difference is negligible. Migrate to Turbo Modules when performance-critical native code needs to keep up with 60fps interactions.
// Performance benchmark pattern
const ITERATIONS = 10000;
const start = Date.now();
for (let i = 0; i < ITERATIONS; i++) {
// Synchronous JSI call
const model = NativeDeviceInfo.getDeviceModel();
}
const elapsed = Date.now() - start;
console.log('10k JSI calls in', elapsed, 'ms');
// Turbo: ~8ms vs Legacy bridge: ~80msQuick Check
Test your understanding of React Native Mobile Development concepts from this lesson.
Lesson Recap
In this lesson you learned: how JSI eliminates JSON serialization overhead from the legacy bridge, how to write a TypeScript spec file that codegen uses to generate native interfaces, and how to implement the generated spec in both Kotlin and Swift. You also saw how to enable the New Architecture and the performance benefits of synchronous JSI calls. Next up we explore async callbacks, promises, and native events.
Impara JavaScript con un tutor IA — gratis
Scrivi ed esegui vero codice nel tuo browser, ricevi aiuto istantaneo da un tutor IA disponibile 24/7, e riprendi da dove hai lasciato sul web o nell'app.
- Corsi
- 30
- Lezioni
- 120
Domande Frequenti
La lezione «Turbo Native Modules con JSI» è gratuita?
Sì — il testo completo di «Turbo Native Modules con JSI» è gratuito qui sul web. Per esercitarvi in modo interattivo (un editor di codice integrato e un tutor IA 24/7) e sbloccare il resto del corso React Native Academy, passa a CoddyKit PRO. Il corso React Native Academy include 4 lezioni in totale.
Cosa imparerò in «Turbo Native Modules con JSI»?
Definisca un file spec TypeScript per un Turbo Native Module, lo implementi in Kotlin e Swift utilizzando l'interfaccia generata da codegen e chiami il modulo in modo sincrono tramite JSI. Eserciti React Native Academy con codice pratico che esegui direttamente nel browser, e un tutor IA 24/7 risponde alle tue domande mentre lavori sulla lezione.
Ho bisogno di esperienza per iniziare React Native Academy?
Non è richiesta alcuna esperienza precedente. React Native Academy su CoddyKit è strutturato per principianti e studenti avanzati, quindi puoi iniziare da qui o dall'inizio e procedere al tuo ritmo. Questa è la lezione 3 di 4.
Quanto tempo richiede la lezione «Turbo Native Modules con JSI»?
La maggior parte delle lezioni CoddyKit richiede circa 5–10 minuti. Ogni lezione è breve e interattiva, quindi fai progressi costanti e riprendi esattamente da dove hai lasciato su web e app.
Posso scrivere ed eseguire codice in questa lezione React Native Academy?
Sì. Ogni lezione React Native Academy include un editor di codice integrato, quindi scrivi ed esegui codice reale direttamente nel tuo browser e ricevi feedback istantaneo dall'IA — nessuna configurazione locale necessaria.
Tutte le lezioni di questo corso
- Scrivere un modulo nativo legacy in Kotlin
- Scrivere un modulo nativo legacy in Swift
- Turbo Native Modules con JSI
- Callback asincrone, Promise ed eventi dal codice nativo