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An open transpiler from Java to TypeScript/JavaScript

1000+ well-typed JavaScript libraries available from Java

Version 2.0.0-rc1

Try it live » Quick start »


package animation;
[...] // imports
/** This program rotates the JSweet logo: try it by clicking on the logo! */
public class RotateLogo {

	public static void main(String[] args) {
		HTMLImageElement image = (HTMLImageElement) document.getElementById("logo");
		image.addEventListener(mousedown, RotateLogo::animate);

	static private double angle = 0;

	static private double animate(MouseEvent mouseEvent) {
		((HTMLElement) = "scale(" + Math.cos(angle) + ",1)";
		return window.requestAnimationFrame(time -> {
			angle = angle >= Math.PI * 2 ? 0 : angle + 0.05;
			if (angle != 0) {

… to JavaScript See TypeScript output

var animation;
(function (animation) {
	/** This program rotates the JSweet logo: try it by clicking on the logo! */
	var RotateLogo = (function () {
		function RotateLogo() {
		RotateLogo.main = function (args) {
			var image = document.getElementById("logo");
			image.addEventListener("mousedown", function (mouseEvent) { return RotateLogo.animate(mouseEvent); });
		RotateLogo.animate = function (mouseEvent) { = "scale(" + Math.cos(RotateLogo.angle) + ",1)";
			return window.requestAnimationFrame(function (time) {
				RotateLogo.angle = RotateLogo.angle >= Math.PI * 2 ? 0 : RotateLogo.angle + 0.05;
				if ((RotateLogo.angle != 0)) {
		RotateLogo.angle = 0;
		return RotateLogo;
	animation.RotateLogo = RotateLogo;
})(animation || (animation = {}));

JSweet leverages TypeScript to bring you the safest and most well-typed way to program JavaScript applications using the Java language and tooling. With our Maven repository, you get instant access to hundreds of well-typed JavaScript libraries in Java. JSweet is an open transpiler, which means that programmers can write extensions to tune the transpiler to support more specific use cases.


Object oriented and well-typed JSweet support most Java language features and semantics. As such, it is fully object oriented and uses Java type system to ensure easy and safe programming.
JavaScript output JSweet generates programmer-friendly JavaScript code.
TypeScript output JSweet generates programmer-friendly TypeScript code, including definitions for well-typed interoperability with TypeScript programs.
Interoperability JSweet can generate JavaScript code free from any Java API. It is designed to ensure low impedance with JavaScript so that it is straightforward to access JSweet-generated APIs/objects from JavaScript, without requiring any other tooling or runtime.
Extensibility JSweet is an open transpiler! It means one can add extensions to JSweet in order to tune the generated code and support more APIs/Libs/Contexts/Use Cases.
JSDoc JSweet transforms JavaDoc comments to JSDoc comments.
Source maps JSweet allows the generation of source maps so that you can debug the original Java code when running within the browser.
Node.js, Angular and modules JSweet supports commonjs modules and is compatible with Node.js. It is also compatible with Angular 2+.


Eclipse integration: the call hierarchy view example.


Debuging Java code right into the browser (or in Eclipse using SDBG).


Getting started

Learn how to use JSweet with Maven, install the Eclipse plugin and write your first JSweet programs. See how to use the Java language and all the associated tools to program WEB and Mobile HTML5 applications using existing JavaScript APIs and frameworks.

Start the tutorial »


Learn by example. Go to the examples page and check out many small JSweet-powered WEB apps, which can be forked on Github. See how to use JavaScript APIs, jQuery, Angularjs, Knockoutjs, Threejs, Nodejs, and many others from Java!

Go to examples »

APIs (candies)

JSweet APIs and libraries (a.k.a. candies) are generated through the most up-to-date TypeScript well-typed APIs on the Web. JSweet relies on the Definitely Typed definition files to create Java APIs for most of the JavaScript frameworks out there!

Go to candies »

Subscribe to JSweet news (low traffic)

Go to our blog.

JSweet is fully open source and independant. Support us and contribute on Github, or make a donation: