Nashorn Engine
Nashorn engine is an open source implementation of the
ECMAScript Edition 5.1 Language Specification.
It also implements many new features introduced in ECMAScript 6
including template strings; let, const, and block scope; iterators
and for..of loops; Map, Set, WeakMap, and WeakSet data types;
symbols; and binary and octal literals. It is written in Java and runs
on the Java Virtual Machine.
Nashorn used to be part of the JDK until Java 14. This project provides a standalone version of Nashorn suitable for use with Java 11 and later.
Nashorn is free software, licensed under GPL v2 with the Classpath exception, just like the JDK.
Documentation
Making Nashorn standalone is still a work in progress. There is no standalone user's guides for it yet. The best current guides are Nashorn-related documents last published by Oracle with Java 14:
(When browsing these guides, mentally substitute org.openjdk.nashorn in place of jdk.scripting.nashorn module name and jdk.nashorn package name.)
Getting Started
Latest version of Nashorn is 15.4, available from Maven Central. You can check the change log to see what's new.
Nashorn is a JPMS module, so make sure it and its transitive dependencies (Nashorn depends on several ASM JARs) are on your application's module path, or appropriately added to a module layer, or otherwise configured as modules.
While standalone Nashorn is primarily meant to be used with Java 15 and later versions, it can also be used with Java versions 11 to 14 that have a built-in version of Nashorn too. See this page for details on use when both versions are present.
Building From Source
Nashorn uses Ant as its build system.
cd make/nashorn
ant jar
will download the dependencies and build the JAR file. Other notable targets are test for running its own internal test suite, or test262-parallel for running the official ECMA-262 test suite for ECMAScript 5.1. You will need to execute ant get-test262 to download the tests into Nashorn's local test directory once.
Contributing
Nashorn is a project under the charter of the OpenJDK. The OpenJDK Bylaws govern our work. The Nashorn project membership can be found on the OpenJDK Census. We welcome patches and involvement from individual contributors or companies. If this is your first time contributing to an OpenJDK project, you will need to review the rules on becoming a Contributor, and sign the Oracle Contributor Agreement (OCA).
Issue tracking
If you think you have found a bug in Nashorn, first make sure that you are testing against the latest version - your issue may already have been fixed. If not, search our issues list in the Java Bug System (JBS) in case a similar issue has already been opened. More information on where and how to report a bug can be found at bugreport.java.com. Use component "Core Libraries" and Subcomponent "jdk.nashorn" when filing an issue.
Discussion
Discussion of Nashorn development happens on the nashorn-dev mailing list.