JarCasting
JSC build scripts for Android
The aim of this project is to provide maintainable build scripts for the JavaScriptCore JavaScript engine and allow the React Native project to incorporate up-to-date releases of JSC into the framework on Android.
This project is based on facebook/android-jsc but instead of rewriting JSC's build scripts into BUCK files, it relies on CMake build scripts maintained in a GTK branch of WebKit maintained by the WebKitGTK team (great work btw!). Thanks to that, with just a small amount of work we should be able to build not only current but also future releases of JSC. An obvious benefit for everyone using React Native is that this will allow us to update JSC for React Native on Android much more often than before (note that facebook/android-jsc uses JSC version from Nov 2014), which is especially helpful since React Native on iOS uses the built-in copy of JSC that is updated with each major iOS release (see this as a reference).
Requirements
- Homebrew (https://brew.sh/)
- GNU coreutils
brew install coreutils - Node
brew install node - Java 8:
brew tap caskroom/versions && brew cask install java8 - Android SDK:
brew cask install android-sdk- Run
sdkmanager --listand install all platforms, tools, buildtool v28.0.3, cmake (android images are not needed) - Set
$ANDROID_HOMEto the correct path (in ~/.bashrc or similar) - Set
export PATH=$PATH:$ANDROID_HOME/platform-tools:$ANDROID_HOME/tools/bin
- Run
- Android NDK r17c: download from NDK Archives
- Set
export ANDROID_NDK=/path/to/android-ndk-r17c
- Set
- Make sure you have Ruby (>2.3), Python (>2.7), Git, SVN, gperf
Build instructions
- Clone this repo
npm run cleanwill clean everything (artifacts, downloaded sources)- Update the version in package.json. The version will be printed by JSC lib as soon as it loads.
- Update the config section under
package.jsonto the desired build configuration - Update patches if needed (don't forget to update the
printVersionpatch in jsc.patch) npm run download: downloads all needed sourcesnpm run start: builds jsc (this might take some time...)
The zipfile containing the android-jsc AAR will be available at /dist. The library is packaged as a local Maven repository containing AAR files that include the binaries.
Distribution
JSC library built using this project is distributed over npm: npm/jsc-android. The library is packaged as a local Maven repository containing AAR files that include the binaries. Please refer to the section below in order to learn how your app can consume this format.
On load, JSC prints the version out to logcat, under "JavaScriptCore.Version" tag.
How to use it with my React Native app
Follow steps below in order for your React Native app to use new version of JSC VM on android:
For React Native version 0.60 and newer
- Update
jsc-android:
yarn add jsc-android
# Or if you would like to try latest version
# yarn add 'jsc-android@canary`
- You're done, rebuild your app and enjoy updated version of JSC on android!
For React Native version 0.59
- Add
jsc-androidto the "dependencies" section in yourpackage.json:
dependencies {
+ "jsc-android": "241213.x.x",
then run npm install or yarn (depending on which npm client you use) in order for the new dependency to be installed in node_modules
- Modify
android/build.gradlefile to add the new local maven repository packaged in thejsc-androidpackage to the search path:
allprojects {
repositories {
mavenLocal()
jcenter()
maven {
// All of React Native (JS, Obj-C sources, Android binaries) is installed from npm
url "$rootDir/../node_modules/react-native/android"
}
+ maven {
+ // Local Maven repo containing AARs with JSC library built for Android
+ url "$rootDir/../node_modules/jsc-android/dist"
+ }
}
}
- Update your app's
build.gradlefile located inandroid/app/build.gradleto add the JSC dependency. Please make sure the dependency is before the React Native dependency.
dependencies {
+ // Make sure to put android-jsc at the top
+ implementation "org.webkit:android-jsc:r241213"
+
compile fileTree(dir: "libs", include: ["*.jar"])
implementation "com.android.support:appcompat-v7:${rootProject.ext.supportLibVersion}"
implementation "com.facebook.react:react-native:+" // From node_modules
}
- Update your app's
build.gradlefile located inandroid/app/build.gradleto use first matched JSC library.
android {
// ...
+ packagingOptions {
+ pickFirst '**/libjsc.so'
+ pickFirst '**/libc++_shared.so'
+ }
}
- You're done - rebuild your app and enjoy the updated version of JSC on Android!
For React Native version 0.58 below
- Add
jsc-androidto the "dependencies" section in yourpackage.json:
dependencies {
+ "jsc-android": "241213.x.x",
then run npm install or yarn (depending which npm client you use) in order for the new dependency to be installed in node_modules
- Modify
android/build.gradlefile to add new local maven repository packaged in thejsc-androidpackage to the search path:
allprojects {
repositories {
mavenLocal()
jcenter()
maven {
// All of React Native (JS, Obj-C sources, Android binaries) is installed from npm
url "$rootDir/../node_modules/react-native/android"
}
+ maven {
+ // Local Maven repo containing AARs with JSC library built for Android
+ url "$rootDir/../node_modules/jsc-android/dist"
+ }
}
}
- Update your app's
build.gradlefile located inandroid/app/build.gradleto force app builds to use new version of the JSC library as opposed to the version specified in react-native gradle module as a dependency:
}
+configurations.all {
+ resolutionStrategy {
+ force 'org.webkit:android-jsc:r241213'
+ }
+}
dependencies {
compile fileTree(dir: "libs", include: ["*.jar"])
+ // ...
+ implementation 'org.webkit:android-jsc-cppruntime:+'
+ // For even older gradle
+ // compile 'org.webkit:android-jsc-cppruntime:+'
- You're done, rebuild your app and enjoy updated version of JSC on android!
International variant
International variant includes ICU i18n library and necessary data allowing to use e.g. Date.toLocaleString and String.localeCompare that give correct results when using with locales other than en-US. Note that this variant is about 6MiB larger per architecture than default.
To use this variant instead replace the third installation step with:
For React Native version 0.60 and newer, your build.gradle should have a flag to enable this feature.
/**
* Use the international variant of JavaScriptCore
* This variant includes the ICU i18n library to make APIs like `Date.toLocaleString`
* and `String.localeCompare` work when using with locales other than en-US.
* Note that this variant is about 6MiB larger per architecture than the default.
*/
- def useIntlJsc = false
+ def useIntlJsc = true
For React Native version 0.59, replace original artifact id with android-jsc-intl
dependencies {
+ // Make sure to put android-jsc at the the first
+ implementation "org.webkit:android-jsc-intl:r241213"
+
compile fileTree(dir: "libs", include: ["*.jar"])
implementation "com.android.support:appcompat-v7:${rootProject.ext.supportLibVersion}"
implementation "com.facebook.react:react-native:+" // From node_modules
}
For React Native version 0.58 below, replace original resolutionStrategy with this.
+configurations.all {
+ resolutionStrategy {
+ eachDependency { DependencyResolveDetails details ->
+ if (details.requested.name == 'android-jsc') {
+ details.useTarget group: details.requested.group, name: 'android-jsc-intl', version: 'r241213'
+ }
+ }
+ }
+}
Testing
See Measurements page that contains synthetic perf test results for the most notable versions of JSC we have tried.
Troubleshooting
Compile errors of the sort:
More than one file was found with OS independent path 'lib/armeabi-v7a/libgnustl_shared.so'
Add the following to your app/build.gradle, under android:
packagingOptions {
pickFirst '**/libgnustl_shared.so'
}
Resources
Credits
Check the list of contributors here. This project is supported by:
