Java to JavaScript Converter
Convert Java code to JavaScript instantly with accurate syntax transformation
Table of Contents
What is Java to JavaScript Converter?
The Java to JavaScript Converter is a free online tool that transforms Java source code into equivalent JavaScript code. While Java and JavaScript are fundamentally different languages (despite the similar names), many syntactic patterns can be directly translated, making migration and learning easier.
Our converter handles common Java constructs including classes, methods, variable declarations, loops, conditionals, and popular API calls like System.out.println to console.log. It's perfect for developers transitioning between languages or learning JavaScript from a Java background.
Instant Conversion
Convert Java to JavaScript in milliseconds with real-time processing
Smart Syntax
Intelligently converts Java patterns to modern JavaScript ES6+
Customizable
Options for arrow functions, const/let, and comment preservation
Secure
Your code is processed securely and never stored
Features
- Class Conversion: Transforms Java classes to ES6 JavaScript classes
- Method Translation: Converts Java methods to JavaScript functions
- Variable Types: Removes Java type declarations and uses let/const
- Console Output: Converts System.out.println to console.log
- String Methods: Translates Java string methods to JavaScript equivalents
- Array Handling: Converts Java arrays and ArrayList to JavaScript arrays
- Loop Conversion: Transforms for-each loops to for...of syntax
- Exception Handling: Converts try-catch blocks with proper syntax
- Lambda Support: Converts Java lambdas to arrow functions
- Comment Preservation: Optionally keeps or removes code comments
How to Convert Java to JavaScript
- Paste Java Code: Enter your Java code in the left editor panel
- Configure Options: Choose whether to preserve comments, use arrow functions, or use const/let
- Click Convert: Press the "Convert to JS" button to transform your code
- Get Results: View the converted JavaScript in the right panel
- Copy or Download: Copy the result to clipboard or download as a .js file
Conversion Examples
Example 1: Hello World
Java:
public class HelloWorld { public static void main(String[] args) { System.out.println("Hello, World!"); } }JavaScript:
class HelloWorld { function main() { console.log("Hello, World!"); } }Example 2: Variables and Methods
Java:
public int add(int a, int b) { int sum = a + b; return sum; } String name = "John"; boolean isActive = true;JavaScript:
add(a, b) { const sum = a + b; return sum; } const name = "John"; const isActive = true;Example 3: Loops and Arrays
Java:
String[] fruits = {"apple", "banana"}; for (String fruit : fruits) { System.out.println(fruit); } for (int i = 0; i < 10; i++) { System.out.println(i); }JavaScript:
const fruits = ["apple", "banana"]; for (let fruit of fruits) { console.log(fruit); } for (let i = 0; i < 10; i++) { console.log(i); }Java vs JavaScript Comparison
| Feature | Java | JavaScript |
|---|---|---|
| Typing | Statically typed (compile-time checking) | Dynamically typed (runtime checking) |
| Execution | Compiled to bytecode, runs on JVM | Interpreted by browser or Node.js |
| OOP | Class-based, strict OOP | Prototype-based, flexible OOP |
| Variables | int, String, boolean, etc. | var, let, const |
| Null Safety | NullPointerException | undefined and null |
| Threading | Multi-threaded with Thread class | Single-threaded with async/await |
| Use Cases | Enterprise apps, Android, backend | Web apps, Node.js, frontend |
Frequently Asked Questions (FAQs)
This converter handles common Java patterns including classes, methods, loops, conditionals, and basic data structures. However, Java-specific features like generics, annotations, interfaces, and multi-threading require manual adjustment. The converter provides a solid starting point that you can refine for complex codebases.
Despite the similar names, Java and JavaScript are completely different languages. Java was developed by Sun Microsystems for general-purpose programming, while JavaScript was created by Netscape for web browsers. The naming similarity was a marketing decision. They have different type systems, execution models, and use cases.
For simple code, the converted JavaScript should work directly. However, Java libraries and APIs don't exist in JavaScript, so you'll need to find equivalent npm packages or rewrite that functionality. The converter focuses on syntax translation; logical equivalents may need manual adjustment.
Some Java features don't have direct JavaScript equivalents: interfaces (use TypeScript for this), generics, access modifiers enforcement, method overloading, checked exceptions, and static typing. The converter removes these constructs, but you may need to restructure your code for JavaScript's paradigm.
Yes, your code is processed securely on our servers and is not stored or logged. The conversion happens in real-time, and your code is immediately discarded after the response is sent. For highly sensitive code, you can review our privacy policy or use the tool for non-sensitive portions.
