Rhino: JavaScript in Java

Rhino is an implementation of JavaScript in Java.

License

Rhino is licensed under the MPL 2.0.

Releases

The current release is Rhino 1.7.15. Please see the Release Notes.

Releases

Rhino 1.7.15	May 3, 2024
Rhino 1.7.14	January 6, 2022
Rhino 1.7.13	September 2, 2020
Rhino 1.7.12	January 13, 2020
Rhino 1.7.11	May 30, 2019
Rhino 1.7.10	April 9, 2018
Rhino 1.7.9	March 15, 2018
Rhino 1.7.8	January 22, 2018
Rhino 1.7.7.2	August 24, 2017
Rhino 1.7.7.1	February 2, 2016
Rhino 1.7.7	June 17, 2015
Rhino 1.7.6	April 15, 2015
Rhino 1.7R5	January 29, 2015

Compatibility table which shows which advanced JavaScript features from ES6, and ES2016+ are implemented in Rhino.

Documentation

Information for script builders and embedders:

Archived

JavaDoc for all the APIs:

https://javadoc.io/doc/org.mozilla/rhino

Code Structure

Rhino 1.7.15 and before were primarily used in a single JAR called "rhino.jar".

Newer releases now organize the code using Java modules. There are four primary modules:

• rhino: The primary codebase necessary and sufficient to run JavaScript code. Required by everything that uses Rhino. In releases after 1.7.15, this module does not contain the "tools" or the XML implementation.
• rhino-tools: Contains the shell, debugger, and the "Global" object, which many tests and other Rhino-based tools use. Note that adding Global gives Rhino the ability to print to stdout, open files, and do other things that may be considered dangerous in a sensitive environment, so it only makes sense to include if you will use it.
• rhino-xml: Adds the implementation of the E4X XML standard. Only required if you are using that.
• rhino-engine: Adds the Rhino implementation of the standard Java ScriptEngine interface. Some projects use this to be able to switch between script execution engines, but for anything even moderately complex it is almost always easier and always more flexible to use Rhino's API directly.

The release contains the following other modules, which are used while building and testing but which are not published to Maven Central:

• rhino-all: This creates an "all-in-one" JAR that includes rhino-runtime, rhino-tools, and rhino-xml. This is what's used if you want to run Rhino using "java jar".
• tests: The tests that depend on all of Rhino and also the external tests, including the Mozilla legacy test scripts and the test262 tests.
• benchmarks: Runs benchmarks using JMH.
• examples: Surprisingly, this contains example code.

Building

Requirements

Rhino requires Java 11 to build. It will (currently) build with Java versions up to at least Java 21. However, not all tools work with Java 21, such as "spotless", so Java 11 is required for regular developers.

How to Build

For normal development, you can build the code, run the static checks, and run all the tests like this:

git submodule init
git submodule update
./gradlew check

To just run the Rhino shell, you can do this from the top-level directory:

./gradlew run -q --console=plain

Alternately, you can build an all-in-one JAR and run that:

./gradlew :rhino-all:build
java -jar rhino-all/build/libs/rhino-all-1.7.16-SNAPSHOT.jar

You can also run the benchmarks:

./gradlew jmh

Code Coverage

The "Jacoco" coverage is enabled by default for the main published modules as well as the special "tests" module. Coverage is generated for each of the main projects separately and available by running

./gradlew jacocoTestReport

To see an aggregated coverage report for everything, which is probably what you want, run

./gradlew testCodeCoverageReport

The result is in: ./tests/build/reports/jacoco/testCodeCoverageReport/html

Releasing and publishing new version

1. Ensure all tests are passing
2. Remove -SNAPSHOT from version in gradle.properties in project root folder
3. Create file gradle.properties in $HOME/.gradle folder with following properties. Populate them with maven repo credentials and repo location.

mavenUser=
mavenPassword=
mavenSnapshotRepo=
mavenReleaseRepo=

4. Run Gradle task to publish artifacts to Maven Central.

./gradlew publish

5. Increase version and add -SNAPSHOT to it in gradle.properties in project root folder.
6. Push gradle.properties to GitHub

Java 16 and later

If you are using a modular JDK that disallows the reflective access to non-public fields (16 and later), you may need to configure the JVM with the --add-opens option to authorize the packages that your scripts shall use, for example:

--add-opens java.desktop/javax.swing.table=ALL-UNNAMED

This is not necessary just to build Rhino -- it may be necessary when embedding it depending on what your project does.

Issues

Most issues are managed on GitHub:

https://github.com/mozilla/rhino/issues

Contributing PRs

To submit a new PR, please use the following process:

• Ensure that your entire build passes "./gradlew check". This will include code formatting and style checks and runs the tests.
• Please write tests for what you fixed, unless you can show us that existing tests cover the changes. Use existing tests, such as those in "testsrc/org/mozilla/javascript/tests", as a guide.
• If you fixed ECMAScript spec compatibility, take a look at test262.properties and see if you can un-disable some tests.
• Push your change to GitHub and open a pull request.
• Please be patient as Rhino is only maintained by volunteers and we may need some time to get back to you.
• Thank you for contributing!

Code Formatting

Code formatting was introduced in 2021. The "spotless" plugin will fail your build if you have changed any files that have not yet been reformatted. Please use "spotlessApply" to reformat the necessary files.

If you are the first person to touch a big file that spotless wants to make hundreds of lines of changes to, please try to put the reformatting changes alone into a single Git commit so that we can separate reformatting changes from more substantive changes.

Currently, you must be building on Java 11 for Spotless to run. We recommend that you have that ready. (We have not been able to figure out a version of Spotless and the Google formatting plugin that it uses that works on many Java versions.)

More Help

GitHub is the best place to go with questions. For example, we use "GitHub discussions":

https://github.com/mozilla/rhino/discussions