QuickJS Android

QuickJS Android wrapper.

Build

git clone --recurse-submodules https://github.com/seven332/quickjs-android.git

Open the folder quickjs-android in Android Studio.

Download

1. Add the JitPack repository to your root build.gradle.

allprojects {
repositories {
...
maven { url 'https://jitpack.io' }
}
}

2. Add quickjs-android dependency to your application build.gradle.

dependencies {
implementation "com.github.seven332:quickjs-android:0.1.0"
}

Usage

Evaluate Javascript Scripts

QuickJSquickJS = newQuickJS.Builder().build();
try (JSRuntimeruntime = quickJS.createJSRuntime()) {
try (JSContextcontext = runtime.createJSContext()) {
Stringscript1 = "" +
"function fibonacci(n) {" +
" if (n == 0 || n == 1) return n;" +
" return fibonacci(n - 1) + fibonacci(n - 2);" +
"}";
// Evaluate a script without return valuecontext.evaluate(script1, "fibonacci.js");
Stringscript2 = "fibonacci(10);";
// Evaluate a script with return valueintresult = context.evaluate(script2, "fibonacci.js", int.class);
assertEquals(55, result);
}
}

Call Java Methods in Javascript Scripts

Non-static methods and static methods are supported. Wrap a Java method as a JSFunction, then add the JSFunction to the JSContext. Call it like a normal Javascript function.

QuickJSquickJS = newQuickJS.Builder().build();
try (JSRuntimeruntime = quickJS.createJSRuntime()) {
try (JSContextcontext = runtime.createJSContext()) {
// Non-static methodIntegerinteger = 0;
JSFunctionzeroCompareTo = context.createJSFunction(integer, Method.create(Integer.class, Integer.class.getMethod("compareTo", Integer.class)));
// Add the function to the global objectcontext.getGlobalObject().setProperty("zeroCompareTo", zeroCompareTo);
assertEquals(-1, (int) context.evaluate("zeroCompareTo(1)", "test.js", int.class));
assertEquals(1, (int) context.evaluate("zeroCompareTo(-1)", "test.js", int.class));
// Static methodJSFunctionjavaAbs = context.createJSFunctionS(Math.class, Method.create(Math.class, Math.class.getMethod("abs", int.class)));
// Add the function to the global objectcontext.getGlobalObject().setProperty("javaAbs", javaAbs);
assertEquals(1, (int) context.evaluate("javaAbs(1)", "test.js", int.class));
assertEquals(1, (int) context.evaluate("javaAbs(-1)", "test.js", int.class));
}
}

Or create a JSFunction with a callback.

QuickJSquickJS = newQuickJS.Builder().build();
try (JSRuntimeruntime = quickJS.createJSRuntime()) {
try (JSContextcontext = runtime.createJSContext()) {
// Create a JSFunction with a callbackJSValueplusFunction = context.createJSFunction((context, args) -> {
inta = args[0].cast(JSNumber.class).getInt();
intb = args[1].cast(JSNumber.class).getInt();
intsum = a + b;
returncontext.createJSNumber(sum);
});
context.getGlobalObject().setProperty("plus", plusFunction);
intresult = context.evaluate("plus(1, 2)", "test.js", Integer.class);
assertThat(result).isEqualTo(3);
}
}

Call Javascript Methods in Java codes

Just evaluate it. Or call JSFunction.invoke().

Promise

Use JSContext.executePendingJob() to execute pending job of promises. You may call JSContext.executePendingJob() several times until it returns false.

QuickJSquickJS = newQuickJS.Builder().build();
try (JSRuntimeruntime = quickJS.createJSRuntime()) {
try (JSContextcontext = runtime.createJSContext()) {
context.evaluate("a = 1;Promise.resolve().then(() => { a = 2 })", "test.js");
assertEquals(1, context.getGlobalObject().getProperty("a").cast(JSNumber.class).getInt());
// Execute the pending jobassertTrue(context.executePendingJob());
assertEquals(2, context.getGlobalObject().getProperty("a").cast(JSNumber.class).getInt());
// No pending jobassertFalse(context.executePendingJob());
}
}

Conversion between Java Values and Javascript Values

Java values are converted to Javascript values when calling Java methods in Javascript scripts. Javascript values are converted to a Java values when receiving return values from evaluated Javascript scripts. QuickJS Android supports primitive types, string, array.

QuickJSquickJS = newQuickJS.Builder().build();
try (JSRuntimeruntime = quickJS.createJSRuntime()) {
try (JSContextcontext = runtime.createJSContext()) {
String[] result = context.evaluate("['hello', 'world']", "test.js", String[].class);
assertArrayEquals(newString[] { "hello", "world" }, result);
}
}

Java Interfaces are also supported.

interfaceCalculator {
doubleplus(doublea, doubleb);
doubleminus(doublea, doubleb);
doublemultiplies(doublea, doubleb);
doubledivides(doublea, doubleb);
voidnoop();
}
QuickJSquickJS = newQuickJS.Builder().build();
try (JSRuntimeruntime = quickJS.createJSRuntime()) {
try (JSContextcontext = runtime.createJSContext()) {
Calculatorcalculator = context.evaluate("" +
"a = {\n" +
" plus: function(a, b) { return a + b },\n" +
" minus: function(a, b) { return a - b },\n" +
" multiplies: function(a, b) { return a * b },\n" +
" divides: function(a, b) { return a / b },\n" +
" noop: function() { }\n" +
"}", "test.js", Calculator.class);
}
}

Use TypeAdapter to support any type you like.

privatestaticclassAtomicIntegerTypeAdapterextendsTypeAdapter<AtomicInteger> {
@OverridepublicJSValuetoJSValue(Depotdepot, Contextcontext, AtomicIntegervalue) {
returncontext.createJSNumber(value.get());
}
@OverridepublicAtomicIntegerfromJSValue(Depotdepot, Contextcontext, JSValuevalue) {
returnnewAtomicInteger(value.cast(JSNumber.class).getInt());
}
}
QuickJSquickJS = newQuickJS.Builder().registerTypeAdapter(AtomicInteger.class, newAtomicIntegerTypeAdapter()).build();
try (JSRuntimeruntime = quickJS.createJSRuntime()) {
try (JSContextcontext = runtime.createJSContext()) {
AtomicIntegeratomicInteger = context.evaluate("1", "test.js", AtomicInteger.class);
assertEquals(1, atomicInteger.get());
}
}

Concept

QuickJS Android uses the similar APIs to QuickJS.

JSRuntime

JSRuntime represents a Javascript runtime corresponding to an object heap. Several runtimes can exist at the same time but they cannot exchange objects. Inside a given runtime, no multi-threading is supported.

-- QuickJS Document

JSContext

JSContext represents a Javascript context (or Realm). Each JSContext has its own global objects and system objects. There can be several JSContexts per JSRuntime and they can share objects, similar to frames of the same origin sharing Javascript objects in a web browser.

-- QuickJS Document

JSValue

JSValue represents a Javascript value which can be a primitive type or an object.

-- QuickJS Document

Available subclasses of JSValue are JSNull, JSUndefined, JSBoolean, JSNumber, JSString, JSObject, JSArray, JSFunction, JSSymbol.

Test

The original tests and benchmarks of QuickJS are in android-test. It's a console-like app running all tests and benchmarks at startup, like make test.