QuickJS For Android/JVM

QuickJS wrapper for Android/JVM.

Feature

• Java types are supported with JavaScript
• Support promise execute
• JavaScript exception handler
• Compile bytecode
• Supports converting JS object types to Java HashMap.
• ESModule (import, export)

Experimental Features Stability not guaranteed.

• Supports ArrayBuffer to a byte array type.

Download

repositories {
  mavenCentral()
}

dependencies {
  // Pick one:

  // 1. Android - Use wrapper in your public API:
  api 'wang.harlon.quickjs:wrapper-android:latest.version'

  // 2. JVM - Use wrapper in your implementation only:
  implementation 'wang.harlon.quickjs:wrapper-java:latest.version'
}

SNAPSHOT

See how to import the snapshot

Including the SNAPSHOT

Snapshots of the current development version of Wrapper are available, which track the latest versions.

To import snapshot versions on your project, add the code snippet below on your gradle file:

repositories {
   maven { url 'https://s01.oss.sonatype.org/content/repositories/snapshots/' }
}

Next, add the dependency below to your module's build.gradle file:

dependencies {
    // For Android
    implementation "wang.harlon.quickjs:wrapper-android:latest-SNAPSHOT"
    // For JVM
    implementation "wang.harlon.quickjs:wrapper-java:latest-SNAPSHOT"
}

Building the Project

This repository use git submodules and so when you are checking out the app, you'll need to ensure the submodules are initialized properly. You can use the --recursive flag when cloning the project to do this.

git clone --recursive https://github.com/HarlonWang/quickjs-wrapper.git

Alternatively, if you already have the project checked out, you can initialize the submodules manually.

git submodule update --init

Usage

Initialization

In Android Platforms:

// You usually need to initialize it before using it..
QuickJSLoader.init();

Refer to here for other platforms.

Create QuickJSContext

QuickJSContext context = QuickJSContext.create();

// evaluating JavaScript
context.evaluate("var a = 1 + 2;");

// destroy QuickJSContext
context.destroy();

Console Support

context.setConsole(your console implementation.);

Supported Types

Java and JavaScript can directly convert to each other for the following basic types

JavaScript	Java
null	null
undefined	null
boolean	Boolean
Number	Long/Int/Double
string	String
Array	JSArray
object	JSObject
Function	JSFunction
ArrayBuffer	byte[](Deep copy)

Since JavaScript doesn't have a long type, additional information about long:

Java --> JavaScript

• The Long value <= Number.MAX_SAFE_INTEGER, will be convert to Number type.
• The Long value > Number.MAX_SAFE_INTEGER, will be convert to BigInt type.
• Number.MIN_SAFE_INTEGER is the same to above.

JavaScript --> Java

• Number(Int64) or BigInt --> Long type

Set Property

Java

QuickJSContext context = QuickJSContext.create();
JSObject globalObj = context.getGlobalObject();
JSObject repository = context.createNewJSObject();
obj1.setProperty("name", "QuickJS Wrapper");
obj1.setProperty("created", 2022);
obj1.setProperty("version", 1.1);
obj1.setProperty("signing_enabled", true);
obj1.setProperty("getUrl", (JSCallFunction) args -> {
    return "https://github.com/HarlonWang/quickjs-wrapper";
});
globalObj.setProperty("repository", repository);
repository.release();

JavaScript

repository.name; // QuickJS Wrapper
repository.created; // 2022
repository.version; // 1.1
repository.signing_enabled; // true
repository.getUrl(); // https://github.com/HarlonWang/quickjs-wrapper

Get Property

JavaScript

var repository = {
	name: 'QuickJS Wrapper',
	created: 2022,
	version: 1.1,
	signing_enabled: true,
	getUrl: (name) => { return 'https://github.com/HarlonWang/quickjs-wrapper'; }
}

Java

QuickJSContext context = QuickJSContext.create();
JSObject globalObject = context.getGlobalObject();
JSObject repository = globalObject.getJSObject("repository");
repository.getString("name"); // QuickJS Wrapper
repository.getInteger("created"); // 2022
repository.getDouble("version"); // 1.1
repository.getBoolean("signing_enabled"); // true
JSFunction fn = repository.getJSFunction("getUrl");
String url = fn.call(); // https://github.com/HarlonWang/quickjs-wrapper
fn.release();
repository.release();

Create JSObject in Java

QuickJSContext context = QuickJSContext.create();
JSObject obj = context.createNewJSObject();
// Need to release, otherwise it will cause a memory leak.
obj.release();

Create JSArray in Java

QuickJSContext context = QuickJSContext.create();
JSArray array = context.createNewJSArray();
array.release();

How to return Function to JavaScript in Java

QuickJSContext context = createContext();
context.getGlobalObject().setProperty("test", args -> (JSCallFunction) args1 -> "123");
context.evaluate("console.log(test()());");

Also, you can view it in QuickJSTest.testReturnJSCallback code

Compile ByteCode

byte[] code = context.compile("'hello, world!'.toUpperCase();");
context.execute(code);

ESModule

Java

// 1. string code mode
context.setModuleLoader(new QuickJSContext.DefaultModuleLoader() {
    @Override
    public String getModuleStringCode(String moduleName) {
       if (moduleName.equals("a.js")) {
           return "export var name = 'Jack';\n" +
                   "export var age = 18;";
       }
       return null;
    }
});

// 2. bytecode mode
context.setModuleLoader(new QuickJSContext.BytecodeModuleLoader() {
    @Override
    public byte[] getModuleBytecode(String moduleName) {
        return context.compileModule("export var name = 'Jack';export var age = 18;", moduleName);
    }
});

JavaScript

import {name, age} from './a.js';

console.log('name：' + name); // Jack
console.log('age：' + age); // 18

Object release

We typically recommend releasing reference relationships actively after using Java objects to avoid memory leaks. Additionally, the engine will release unreleased objects when destroy, but this timing may be a bit later.

JSFunction func = xxx.getJSFunction("test");
func.call();
func.release();

JSObject obj = xxx.getJSObject("test");
int a = obj.getString("123");
obj.release();

// If the JSFunction does not need to handle the return value, it is recommended to call the following method.
jsFunction.callVoid(xxx);

It's important to note that if the result is being returned for use in JavaScript, there is no need to release it.

context.getGlobalObject().setProperty("test", new JSCallFunction() {
  @Override
  public Object call(Object... args) {
    JSObject ret = context.createNewJSObject();
    // There is no need to call the release method here.
    // ret.release();
    return ret;
  }
});

R8 / ProGuard

If you are using R8 the shrinking and obfuscation rules are included automatically.

ProGuard users must manually add the options from consumer-rules.pro.

Concurrency

JavaScript runtimes are single threaded. All execution in the JavaScript runtime is guaranteed thread safe, by way of Java synchronization.

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Reference

• quickjs-java
• quack
• quickjs-android