Module constants (old arch)

info

You may notice, that JS specs contain codegen-related methods, classes, types, etc. to make things more future-proof.

That's because:

• those elements are available since RN older versions (even from v0.65)
• those elements are falling back to "old architecture" implementation (e.g. codegenNativeComponent)
• it introduces type safety for exposed native parts on JS side
• it's much easier to keep single specification on JS side - when old arch will be dropped, there'll be no need to change anything on JS side

So to make it easier, let's use them, to get you more familiar with it 👍

Constants declaration

JS Spec

src/NativeMyAwesomeModule.ts

import type { TurboModule } from 'react-native';
import { TurboModuleRegistry } from 'react-native';

// ...

export interface Spec extends TurboModule {
  getConstants(): { ALONSO: string, HAMILTON: string, LATIFI: string, VERSTAPPEN: string }
}

// TurboModuleRegistry uses NativeModules['MyAwesomeModule'] on old arch
export default TurboModuleRegistry.getEnforcing<Spec>('MyAwesomeModule');

iOS Spec

ios/NativeMyAwesomeModule.mm

- (NSDictionary *)getConstants {
    return @{
        @"ALONSO": @"You always have to leave the space!",
        @"HAMILTON": @"Dream the impossible!",
        @"LATIFI": @"I don't know what happened there... I'm fine",
        @"VERSTAPPEN": @"Don't forget to sanitise!"
    };
}

Android Spec

Kotlin

android/src/main/newarch/com/myawesomeapp/NativeMyAwesomeModule.kt

override fun getConstants(): MutableMap<String, Any> {
    return mutableMapOf(
        "ALONSO" to "You always have to leave the space!",
        "HAMILTON" to "Dream the impossible!",
        "LATIFI" to "I don't know what happened there... I'm fine",
        "VERSTAPPEN" to "Don't forget to sanitise!"
    )
}

Java

android/src/main/newarch/com/myawesomeapp/NativeMyAwesomeModule.java

import java.util.HashMap;
import java.util.Map;

// ...

@Override
public Map<String, Object> getConstants() {
    final Map<String, Object> map = new HashMap<>();
    map.put("ALONSO", "You always have to leave the space!");
    map.put("HAMILTON", "Dream the impossible!");
    map.put("LATIFI", "I don't know what happened there... I'm fine");
    map.put("VERSTAPPEN", "Don't forget to sanitise!");
    return map;
}