v1.9.0

December 22, 2025

This release represents about a year of work on Rhino by a growing team of contributors.

Some of the improvements include:

• Compatibility improvements in areas like destructuring and spread syntax.
• Performance improvements from 10 to 30% in benchmarks like Delta Blue, Earley-Boyer, and Crypto in both interpreted and compiled mode
• Better support for generics and other things when Java integration is used.

Some other improvements:

JavaScript Language Updates:

• ES6+: Significant advancements in destructuring, spread syntax for
  arrays/objects, Symbol API, and improved let/const scoping.
  TypedArray.from/of and BigInt.asUintN/asIntN fixes.
• RegExp: New features like named capture groups, lookbehind
  assertions, and Unicode mode support.
• Future ES (ES2024/2025): Early implementation of proposals such as
  Promise.withResolvers, Promise.try, ArrayBuffer transfer methods, and
  new Set methods.

Core Engine Enhancements:

• Major Refactoring: Extensive migration of built-in objects to a
  lambda-based architecture and a comprehensive overhaul of the
  interpreter bytecodes for better performance and maintainability.
• Concurrency & Interop: Continued focus on thread safety improvements
  and enhanced Java interoperability, including better generics
  support.

Going forward -- we have lots of plans for Rhino, including some changes that may
affect compatibility for projects that embed Rhino into larger frameworks. We think
that these changes will be worth it because they will unlock better language
compatibility and performance.

As such, the next version going forward will be 2.0.0-SNAPSHOT.

Thanks to everyone who contributed!

v1.8.1

December 2, 2025

These releases fix a bug in the code that formats floating-point numbers into strings
that could result in very bad performance in some cases.

We recommend that all users of Rhino upgrade to release 1.8.1 if possible,
and upgrade to Java 17 or 21.

Users who need an older release, or who cannot yet leave Java 8, can also
use 1.7.15.1 or 1.7.14.1.

v1.8.0

January 2, 2025

Rhino 1.8.0 contains some significant changes, so we're incrementing the final version number for the first time in a very long time. Here are a few highlights:

• Rhino now requires Java 11 minimum. We currently test against Java 11, 17, and 21.
• Rhino has been broken down into individual Java modules that are properly encapsulated as Java Modules. See README.md for a breakdown of which modules are which -- short answer is that everyone will need the "rhino" module and many will need others.
• Older code not able to adapt to using multiple JARS can still use the "rhino-all" module, which publishes an "all-in-one" JAR like the old "rhino.jar".
• The default language level is "VERSION_ES6". That means that modern JavaScript features supported by Rhino will work by default.
• There are big improvements in compatibility, including support for "super", reflect and proxy, and lots of other language features. See the compatibility table for the details.

Thanks to all who contributed -- we had 24 contributors to this release, with some new contributors who added significant capabilities. Please keep the contributions and attention coming!

v1.7.15.1

December 2, 2025

These releases fix a bug in the code that formats floating-point numbers into strings
that could result in very bad performance in some cases.

We recommend that all users of Rhino upgrade to release 1.8.1 if possible,
and upgrade to Java 17 or 21.

Users who need an older release, or who cannot yet leave Java 8, can also
use 1.7.15.1 or 1.7.14.1.