React Native JavaScriptCore

Opt-in to use JavaScriptCore runtime in React Native.

_Note: JavaScriptCore has been extracted from core react-native as a part of Lean Core JSC RFC(PR)._

Installation

> [!IMPORTANT]
> This library only supports React Native 0.79 and above with new architecture enabled.

``sh
yarn add @react-native-community/javascriptcore
`

$3

Install pods:

`sh
cd ios && USE_THIRD_PARTY_JSC=1 USE_HERMES=0 bundle exec pod install
`
> [!NOTE]
> Note: USE_THIRD_PARTY_JSC=1 is required to use JavaScriptCore from this package until JavaScriptCore is removed from core react-native.

$3

Add the following to your android/gradle.properties:

`properties


Disable Hermes

hermesEnabled=false

Enable third-party JSC

useThirdPartyJSC=true
`

Usage

$3

Open AppDelegate.swift and overwrite createJSRuntimeFactory method:

`diff
import React
import React_RCTAppDelegate
import ReactAppDependencyProvider
import UIKit
+import ReactJSC

// AppDelegate code

class ReactNativeDelegate: RCTDefaultReactNativeFactoryDelegate {
override func sourceURL(for bridge: RCTBridge) -> URL? {
self.bundleURL()
}

override func bundleURL() -> URL? {
#if DEBUG
RCTBundleURLProvider.sharedSettings().jsBundleURL(forBundleRoot: "index")
#else
Bundle.main.url(forResource: "main", withExtension: "jsbundle")
#endif
}

+ override func createJSRuntimeFactory() -> JSRuntimeFactory {
+ jsrt_create_jsc_factory() // Use JavaScriptCore runtime
+ }
}
`

$3

Open MainApplication.java and overwrite getJavaScriptExecutorFactory method:

`diff
+import io.github.reactnativecommunity.javascriptcore.JSCExecutorFactory
+import io.github.reactnativecommunity.javascriptcore.JSCRuntimeFactory

class MainApplication : Application(), ReactApplication {

override val reactNativeHost: ReactNativeHost =
object : DefaultReactNativeHost(this) {
override fun getPackages(): List =
PackageList(this).packages.apply {
// Packages that cannot be autolinked yet can be added manually here, for example:
// add(MyReactNativePackage())
}

override fun getJSMainModuleName(): String = "index"

override fun getUseDeveloperSupport(): Boolean = BuildConfig.DEBUG

override val isNewArchEnabled: Boolean = BuildConfig.IS_NEW_ARCHITECTURE_ENABLED
override val isHermesEnabled: Boolean = BuildConfig.IS_HERMES_ENABLED

+ override fun getJavaScriptExecutorFactory(): JavaScriptExecutorFactory =
+ JSCExecutorFactory(packageName, AndroidInfoHelpers.getFriendlyDeviceName())
}

+ override val reactHost: ReactHost
+ get() = getDefaultReactHost(applicationContext, reactNativeHost, JSCRuntimeFactory())

override fun onCreate() {
super.onCreate()
SoLoader.init(this, OpenSourceMergedSoMapping)
if (BuildConfig.IS_NEW_ARCHITECTURE_ENABLED) {
// If you opted-in for the New Architecture, we load the native entry point for this app.
load()
}
}
}
``

Maintainers

- Callstack – A Total Software Engineering Consultancy that transforms organizations and teams through transformative apps.
- Expo - An open-source platform for making universal native apps for Android, iOS, and the web with JavaScript and React.

$3

Special thanks to the team who worked on the initial extraction of JavaScriptCore from core react-native:

- Riccardo Cipolleschi
- Nicola Corti
- Kudo Chien
- Oskar Kwaśniewski
- jsc-android - This project uses jsc-android under the hood, which is supported by Expo, Software Mansion, and Wix.

License

Everything inside this repository is MIT licensed.