How to access Javascript module with Duktape in Android

Accessing JavaScript Modules with Duktape in Android

Duktape is a lightweight and embeddable JavaScript engine. This article provides a step-by-step guide on how to access JavaScript modules using Duktape within your Android applications.

Prerequisites

• Android Studio
• A basic understanding of Java and Android development
• Knowledge of JavaScript modules

Setting up Duktape

1. Include Duktape Library

Download the Duktape library from its official website: https://duktape.org/

Add the Duktape library as a dependency in your Android project. You can achieve this by using Gradle:

dependencies {
implementation 'org.duktape:duktape:1.7.0' // Replace with the desired version
}

2. Initialize Duktape Engine

Duktape duktape = new Duktape();

Accessing JavaScript Modules

1. Loading Modules

Duktape allows loading JavaScript modules using the duktape.modLoad method:

duktape.modLoad("myModule"); 

This line assumes that “myModule” is a JavaScript module file located in the appropriate directory within your Android project. Replace “myModule” with the actual name of your module file.

2. Calling Functions

Once a module is loaded, you can access its functions using the following steps:

• Get the module object: Object moduleObject = duktape.getGlobalObject("myModule");
• Call the function: Object result = duktape.callMethod(moduleObject, "myFunction", args);

Replace “myFunction” with the name of the function you want to call. “args” is an array of arguments to pass to the function.

Example: Using a JavaScript Module

1. JavaScript Module (myModule.js)

function add(a, b) {
    return a + b;
}

module.exports = {
    add: add
};

2. Android Java Code

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Duktape duktape = new Duktape();
        duktape.modLoad("myModule"); // Load the JavaScript module

        Object moduleObject = duktape.getGlobalObject("myModule");
        Object result = duktape.callMethod(moduleObject, "add", 10, 20);

        Log.d("MainActivity", "Result: " + duktape.toString(result)); // Output: Result: 30
    }
}

Conclusion

Duktape provides a seamless way to integrate JavaScript modules into your Android apps. This approach can be valuable for scenarios such as:

• Extending functionality with pre-built JavaScript libraries
• Improving application logic and performance
• Implementing complex business logic in JavaScript