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Exploring the Java 11 JavaScript Engine


A JavaScript engine is a software component that interprets and executes JavaScript code. It provides the runtime environment for JavaScript to run on different platforms. JavaScript engines are essential for running JavaScript code in web browsers and other applications.

The Java 11 JavaScript engine, also known as Nashorn, is a built-in JavaScript engine in Java 11 and earlier versions. It allows developers to embed and execute JavaScript code within Java applications. This integration of JavaScript and Java provides several benefits, such as the ability to leverage existing Java libraries and frameworks, enhanced scripting capabilities, and increased flexibility in application development.

The Java 11 JavaScript engine is significant because it enables developers to combine the power of Java and JavaScript in a seamless manner. It allows for the execution of JavaScript code alongside Java code, making it easier to build complex applications that require both languages. The engine's presence in the Java ecosystem opens up a wide range of possibilities for developers to create innovative and dynamic applications.

Embedding JavaScript in Java Applications

Embedding JavaScript code within Java applications can provide several benefits.

One advantage is the ability to leverage existing JavaScript libraries and frameworks within a Java project. This allows developers to take advantage of the vast JavaScript ecosystem and reuse code that has already been written.

Another benefit is the flexibility to dynamically execute JavaScript code at runtime. This can be useful for scenarios where certain logic needs to be customizable or configurable without requiring a full application deployment. By embedding JavaScript, developers can provide scripting capabilities to end users or allow runtime customization of application behavior.

To load and execute JavaScript code in Java, one approach is to use the GraalVM. GraalVM is a high-performance runtime that supports multiple programming languages, including JavaScript. It provides a JavaScript engine that can be embedded within Java applications.

To load and execute JavaScript code using the GraalVM, the Context class from the org.graalvm.polyglot package can be used. This class allows you to create a new context for executing JavaScript code. Here is an example:

import org.graalvm.polyglot.Context;
import org.graalvm.polyglot.Value;

public class JavaScriptExample {
    public static void main(String[] args) {
        // Create a new context
        Context context = Context.newBuilder().build();

        // Execute JavaScript code
        Value result = context.eval("js", "var x = 10; x * 2;");

        // Get the result
        int multipliedValue = result.asInt();
        System.out.println(multipliedValue); // Output: 20

In the above example, we create a new context using Context.newBuilder().build(). We then use the eval method of the context to execute JavaScript code. The first argument to eval specifies the language (in this case, "js" for JavaScript), and the second argument is the actual JavaScript code to be executed. The result of the evaluation is stored in a Value object, which can be accessed and manipulated as needed.

This is just a basic example of how to load and execute JavaScript code in Java using the GraalVM. The GraalVM provides many more features and capabilities for integrating JavaScript and Java, such as passing data between the two languages and accessing Java objects from JavaScript code.

By embedding JavaScript code within Java applications using the GraalVM, developers can harness the power of both languages and create more dynamic and flexible applications.

Leveraging the Nashorn Engine

The Nashorn engine is a JavaScript engine that was introduced in Java 8 and is still available in Java 11. It is built on top of the Java Virtual Machine (JVM) and provides a way to execute JavaScript code within Java applications.

Nashorn is known for its high performance and compatibility with the ECMAScript 5.1 specification. It supports various JavaScript features such as functions, objects, arrays, regular expressions, and more.

To use the Nashorn engine in Java applications, you can simply import the necessary classes and create an instance of the ScriptEngine class. This class allows you to evaluate JavaScript code and interact with it from your Java code.

Here's an example of how to use the Nashorn engine to execute JavaScript code within a Java application:

import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class NashornExample {
    public static void main(String[] args) {
        ScriptEngineManager manager = new ScriptEngineManager();
        ScriptEngine engine = manager.getEngineByName("nashorn");

        try {
            // Evaluate JavaScript code
            engine.eval("print('Hello, Nashorn!')");
        } catch (ScriptException e) {

In this example, we first create an instance of ScriptEngineManager, which is used to obtain the Nashorn engine implementation. Then, we retrieve the Nashorn engine by its name "nashorn". Finally, we use the eval method of the ScriptEngine class to evaluate the JavaScript code and print "Hello, Nashorn!" to the console.

The Nashorn engine can be used for various purposes such as scripting, dynamic code execution, and testing. It provides a seamless integration between JavaScript and Java, allowing developers to leverage the strengths of both languages in their applications.

It's important to note that starting from Java 11, the Nashorn engine is deprecated and no longer actively maintained. The GraalVM JavaScript engine, which offers better performance and compatibility, is recommended for new projects. However, the Nashorn engine can still be used in legacy applications that require it.

Overall, the Nashorn engine in Java 11 provides a powerful and convenient way to execute JavaScript code within Java applications. It offers a wide range of features and capabilities, making it a valuable tool for developers working in a mixed-language environment.

Exploring JavaScript Engine in Various Scenarios

The Java 11 JavaScript engine offers a wide range of applications in various scenarios. Let's explore how it can be used in different contexts:

Server-side Scripting

The Java 11 JavaScript engine can be leveraged for server-side scripting, allowing developers to execute JavaScript code on the server. This opens up opportunities for building dynamic and interactive web applications. For example, you can use the engine to handle server-side form validation, generate dynamic HTML content, or implement custom business logic.

Integration in Build Tools and Automation Scripts

The Java 11 JavaScript engine can be integrated into build tools and automation scripts, providing a powerful scripting language for tasks such as build automation, deployment, and testing. For instance, you can use JavaScript to define custom build tasks, automate repetitive tasks, or manipulate data during the build process.

Utilizing JavaScript in JavaFX Applications

The Java 11 JavaScript engine can also be used to incorporate JavaScript into JavaFX applications. This allows developers to enhance their JavaFX applications with dynamic behavior and interactivity. JavaScript can be used to handle user interactions, manipulate the UI, or even implement complex animations and visual effects.

Real-World Examples and Use Cases

To illustrate the versatility of the Java 11 JavaScript engine, let's consider some real-world examples and use cases.

  • In a server-side scripting scenario, imagine a social media platform that allows users to post comments. The Java 11 JavaScript engine can be used to filter and moderate user comments, ensuring that only appropriate content is displayed.

  • In the context of build tools and automation scripts, consider a continuous integration and deployment pipeline. JavaScript can be used to define custom deployment scripts, handle versioning, and automate the deployment process.

  • For a JavaFX application, imagine a data visualization tool that displays real-time stock market data. The Java 11 JavaScript engine can be used to dynamically update the charts and graphs based on the incoming data, providing a responsive and interactive user experience.

By exploring these scenarios and use cases, developers can harness the power of the Java 11 JavaScript engine to create innovative and efficient solutions across different domains.


In this article, we have explored the Java 11 JavaScript engine and its capabilities. We have discussed how to embed JavaScript code within Java applications using the GraalVM and how to leverage the Nashorn engine for executing JavaScript code within Java.

The Java 11 JavaScript engine provides numerous benefits, including the ability to seamlessly integrate JavaScript and Java code, which allows for enhanced flexibility and productivity. The engine can be used in various scenarios, such as server-side scripting, build tools, automation scripts, and even in JavaFX applications.

By experimenting with the Java 11 JavaScript engine, developers can unlock new possibilities in their projects. They can take advantage of the rich ecosystem of JavaScript libraries and frameworks while leveraging the power and stability of the Java platform.

We encourage readers to explore the capabilities of the Java 11 JavaScript engine and discover the potential it holds for their own projects.