Android

Yolk on Android is powered by the QuickJS engine, providing a lightweight and high-performance environment for shared TypeScript logic.

Architecture

The Android implementation mirrors the Apple targets by using a buffer-only bridge. Data is transferred between the Kotlin runtime and the QuickJS engine via raw ByteArray and ByteBuffer objects, avoiding the overhead of JSON serialization.

JS Engine: QuickJS

We use app.cash.quickjs:quickjs-android. QuickJS is ideal for Android because:

• Low Memory Footprint: Significantly lighter than V8 or JSC.
• Fast Startup: Near-instant initialization.
• Modern JS Support: Excellent support for ES2023 features and Promises.

Data Transfer (YolkBin)

All communication uses the YolkBin TLV binary protocol. In Kotlin, this is implemented using java.nio.ByteBuffer, allowing for efficient byte-level manipulation.

Zero-Copy (Direct Buffers)

When passing large datasets from Kotlin to JS, we utilize ByteBuffer.allocateDirect(). This memory lives outside the Java heap, and the QuickJS bridge can access it with minimal intermediate copying.

Example: Native Module

To create a native module in Android, implement the YolkModule interface:

class NativeStorageModule : YolkModule {
    override val name: String = "Storage"
 
    override suspend fun handle(method: String, args: ByteBuffer): ByteBuffer {
        val argArray = (YolkBin.decode(args) as? List<*>) ?: emptyList<Any?>()
        
        return when (method) {
            "save" -> {
                val key = argArray[0] as String
                val data = argArray[1] as ByteBuffer
                // Perform native storage operation...
                YolkBin.encode(true)
            }
            else -> throw IllegalArgumentException("Unknown method $method")
        }
    }
}

State Management

The Android implementation supports the Reactive SSOT model. By registering a NativeObserverModule in your YolkRuntime, your Jetpack Compose UI can reactively observe the JS state:

val runtime = YolkRuntime()
runtime.register(NativeObserverModule { map ->
    // Update your Compose state or ViewModel
    val newState = PlaygroundState(
        count = (map["count"] as? Double)?.toInt() ?: 0,
        // ...
    )
})