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This project is a transpiler able to transform your Java codebase to TypeScript and then to JavaScript to ultimatly run Java code in the browser.

NB: JDK 8 or below

The goal of J2TS is to share a codebase between Java, TypeScript and Javascript. This is especially helpful for sharing domain classes, data structures, and complex algorithms.

The goal of J2TS is not to develop a UI in Java. There are better projects for this. J2TS focus on performance and readability of the generated TypeScript code.

The easiest way to get started with J2TS is using the maven plugin. Hereafter is a simple snippet of usage:

<plugin>
    <groupId>com.datathings</groupId>
    <artifactId>j2ts-mavenplugin</artifactId>
    <version>${j2ts.version}</version>
    <executions>
        <execution>
            <id>transpile</id>
            <goals>
                <goal>java2ts</goal>
            </goals>
            <configuration>
                <name>sample</name>
                <copyJRE>true</copyJRE>
            </configuration>
        </execution>
    </executions>
</plugin>

By default the Java source directory is src/main/java and the generated-sources is target/generated-sources/java2ts.

These values can be overriden as follows:

<source>${basedir}/../api/src/main/java</source>
<target>${basedir}/target/generated-sources</target>

A full sample project is hosted here

This project can be compiled through the following command

mvn clean install

Make sure you have NodeJS, NPM and TypeScript installed on your system. To install TypeScript just tape the following command in your console:

npm i -g typescript

Then go to the target/classes directory and open the index.html in you browser to see how to use the generated code.

Currently, in order to keep the JRE.js as lightweight as possible, only a subSet of the JRE is supported. For instance, we support most common structures sucj as ArrayList and HashMap, but not all advanced once such as ConcurrentQueue and so on. However, if you face a limitation due to the lake of one JRE class, don't worry this is very easy to extend.

In a nutshell, update the base JRE.TS file here:

transpiler/src/main/resources/java.ts

To add your class with the same name than in Java. Finally in case of inferred package please also update this class:

transpiler/src/main/java/java2typescript/helper/TypeHelper.java#L162

Finally to provide a new JRE class permanently, please do a push request.