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Rhino: JavaScript in Java

Rhino (234581759)

Rhino is an implementation of JavaScript in Java.


Rhino is licensed under the MPL 2.0.


The current release is Rhino 1.7.14. Please see the Release Notes.

Rhino 1.7.14January 6, 2022
Rhino 1.7.13September 2, 2020
Rhino 1.7.12January 13, 2020
Rhino 1.7.11May 30, 2019
Rhino 1.7.10April 9, 2018
Rhino 1.7.9March 15, 2018
Rhino 1.7.8January 22, 2018
Rhino 24, 2017
Rhino 2, 2016
Rhino 1.7.7June 17, 2015
Rhino 1.7.6April 15, 2015
Rhino 1.7R5January 29, 2015

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

GitHub Action Status



Information for script builders and embedders:


JavaDoc for all the APIs:

More resources if you get stuck:


How to Build

Rhino builds with Gradle. Here are some useful tasks:

./gradlew jar

Build and create Rhino jar in the buildGradle/libs directory.

git submodule init
git submodule update
./gradlew test

Build and run all the tests, including the official ECMAScript Test Suite. See Running tests for more detailed info about running tests.

./gradlew testBenchmark

Build and run benchmark tests.

Releasing and publishing new version

  1. Ensure all tests are passing
  2. Remove -SNAPSHOT from version in in project root folder
  3. Create file in $HOME/.gradle folder with following properties. Populate them with maven repo credentials and repo location.
  1. Run Gradle task to publish artifacts to Maven Central.
./gradlew publish
  1. Increase version and add -SNAPSHOT to it in in project root folder.
  2. Push to GitHub


Rhino can run as a stand-alone interpreter from the command line:

java -jar buildGradle/libs/rhino-1.7.12.jar -debug -version 200
Rhino 1.7.9 2018 03 15
js> print('Hello, World!');
Hello, World!

There is also a "rhino" package for many Linux distributions as well as Homebrew for the Mac.

You can also embed it, as most people do. See below for more docs.

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


Most issues are managed on GitHub:

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 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.

Warning: If you build with Java 16 or later, you need to apply a workaround for a "spotless" issue. Otherwise, the task will be disabled and your PR may fail.

The following must be added to your

org.gradle.jvmargs=--add-exports jdk.compiler/ \
 --add-exports jdk.compiler/ \
 --add-exports jdk.compiler/ \
 --add-exports jdk.compiler/ \
 --add-exports jdk.compiler/

For more details, see diffplug/spotless#834 (comment)

More Help

The Google group is the best place to go with questions:!forum/mozilla-rhino