JavaScriptCore for Android (React Native)

250231.0.0 · active · verified Sun Apr 19

jsc-android provides pre-built versions of JavaScriptCore (JSC) for integration into React Native applications running on the Android platform. It is a critical native dependency for React Native's JavaScript runtime on Android, allowing developers to use a modern and optimized JavaScript engine. The project is actively maintained by the React Native community, with releases tied to WebKitGTK updates and React Native compatibility. Recent stable versions like `v294992.0.0` (as of its release) include updates to WebKitGTK and React Native compatibility. Its key differentiator is providing an up-to-date, performant JSC engine for Android, often replacing older system-provided WebView JavaScript engines. This approach allows for more frequent JSC updates on Android, aligning with how React Native on iOS utilizes the built-in, frequently updated JSC.

Common errors

```
Minimum supported Android SDK is 21, but project minSdkVersion is lower.
```
cause The project's `minSdkVersion` in `build.gradle` is set below 21, which conflicts with `jsc-android` requirements from version `294992.0.0` onwards.

fix Increase `minSdkVersion` to 21 or higher in your `android/app/build.gradle` file.
```
Could not find `org.webkit:android-jsc-intl:+` or `org.webkit:android-jsc:+`.
```
cause This usually indicates that the Maven repository for `jsc-android` is not correctly configured in your `android/build.gradle` or there's a typo in the dependency declaration.

fix Add `maven { url "$rootDir/../node_modules/jsc-android/dist" }` to your `allprojects.repositories` block in `android/build.gradle`. Ensure the dependency in `app/build.gradle` is `implementation "org.webkit:android-jsc-intl:+"`.
```
Native crash in JavaScriptCore (JSC) on `ARM64` devices.
```
cause Older versions of `jsc-android` had known issues leading to crashes on `ARM64` architecture devices.

fix Upgrade `jsc-android` to version `250230.2.1` or later, which includes fixes for `arm64` crashes.
```
More than one file was found with OS independent path 'lib/armeabi-v7a/libgnustl_shared.so' (or similar native library conflict).
```
cause Multiple dependencies are trying to include the same native library (`.so` file), leading to an APK packaging conflict during the Android build.

fix Add `packagingOptions { pickFirst '**/libgnustl_shared.so' }` (or the conflicting file path) to your `android` block in `app/build.gradle`.

Warnings

breaking From `v294992.0.0` onwards, the minimum supported Android SDK version is 21. Projects targeting an SDK version below 21 will fail to build.
Fix: Update your `minSdkVersion` to 21 or higher in `android/app/build.gradle`.
breaking Starting with `v294992.0.0`, only the `Intl` variant (`org.webkit:android-jsc-intl`) is officially supported and distributed. Attempting to use the non-Intl variant or older `android-jsc` artifact might lead to build failures or missing internationalization features.
Fix: Ensure your `android/app/build.gradle` specifies `implementation "org.webkit:android-jsc-intl:+"` and that any `resolutionStrategy` is updated accordingly.
gotcha Earlier versions of `jsc-android` (prior to `v250230.2.1`) were known to cause crashes on `arm64` devices due to issues in the underlying WebKitGTK or NDK versions used for compilation.
Fix: Upgrade to `jsc-android@250230.2.1` or a newer version to benefit from crash fixes for `arm64` architectures.

Install

npm install jsc-android npm
yarn add jsc-android yarn
pnpm add jsc-android pnpm

Imports

JavaScriptCore Runtime
wrong:
```
import JSC from 'jsc-android';
```
correct:
```
/* No direct JavaScript/TypeScript import statement for jsc-android. */
```
This package is a native Android dependency providing the JavaScript execution environment for React Native. It is integrated at the Android build level (via `build.gradle`) and does not expose symbols for direct import into JavaScript or TypeScript code. Developers interact with its presence through the React Native build system.

Quickstart

This code illustrates a basic React Native application that implicitly uses `jsc-android` as its JavaScript runtime on Android. It highlights that no direct JavaScript/TypeScript imports are needed, as `jsc-android` is a native build dependency. The description also guides users to verify its inclusion via the Android project's `build.gradle` file.

import React from 'react';
import { View, Text, StyleSheet, SafeAreaView } from 'react-native';

const App = () => {
  return (
    <SafeAreaView style={styles.container}>
      <View style={styles.content}>
        <Text style={styles.title}>Welcome to React Native!</Text>
        <Text style={styles.subtitle}>
          Your JavaScript code on Android is powered by{' '}
          <Text style={styles.highlight}>jsc-android</Text>.
        </Text>
        <Text style={styles.instruction}>
          jsc-android is implicitly included as a native dependency in most React Native projects.
          To verify the version used, check your Android project's `app/build.gradle` file for a
          dependency similar to `implementation "org.webkit:android-jsc-intl:+"`.
        </Text>
      </View>
    </SafeAreaView>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#f5f5f5',
  },
  content: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    padding: 20,
  },
  title: {
    fontSize: 24,
    fontWeight: 'bold',
    marginBottom: 10,
    color: '#333',
  },
  subtitle: {
    fontSize: 18,
    textAlign: 'center',
    marginBottom: 20,
    color: '#555',
  },
  highlight: {
    fontWeight: 'bold',
    color: '#007bff',
  },
  instruction: {
    fontSize: 14,
    textAlign: 'center',
    color: '#777',
    marginTop: 15,
  },
});

export default App;

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