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mozilla/rhino

Rhino is an open-source implementation of JavaScript written entirely in Java

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Summary Information

Updated 57 minutes ago
Type:Library / SDKCategory(s):Runtimes & WebAssemblyProgramming Languages & CompilersLanguages & Runtimes
Added to GitGenius on September 14th, 2026
Created on May 12th, 2011
Open Issues & Pull Requests: 328 (+0)
GitHub issues: Enabled
Number of forks: 939
Total Stargazers: 4,639 (+0)
Total Subscribers: 167 (+0)

Repository Insights (GitGenius)

Median issue/PR response: 23.5 hours
Mean response time: 162.3 days
90th percentile: 613.6 days
Tracked items: 178

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Maintainer activity

3 people did triage or write work on this repository in the last 12 months.

Counts unlabeled, assigned, unassigned, milestoned, demilestoned, locked, unlocked over the last 12 months. These are issue and pull request events that require triage or write permission. Commits and code review are not counted. labeled and renamed are excluded because GitHub issue forms record the issue author as the actor. Figures from October 11, 2026. This count is not comparable across projects: each project's automation decides which of these events a person emits.

How this project is maintained

About 15% of issues opened in the past year have never received a reply. 72% of open issues come from outside the core team, so the backlog reflects real-world use rather than internal planning. Work labelled "bug" is answered fastest, typically in about 7 days, while "feature" waits about 13 months. Only 43% of issues opened in the past year have been closed. Three people close 72% of everything that gets resolved.

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Issue Activity (beta)

Open issues: 103
New in 7 days: 0
Closed in 7 days: 0
Avg open age: 889 days
Stale 30+ days: 100
Stale 90+ days: 97

Recent activity

Opened in 7 days: 0
Closed in 7 days: 0
Comments in 7 days: 0
Events in 7 days: 0

Top labels

  • Ecma Incompatibility (53)
  • feature (34)
  • bug (24)
  • good first issue (16)
  • enhancement (7)
  • Java Interop (5)
  • Regression (5)
  • Android (4)

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Detailed Description

Rhino is a JavaScript engine that implements the JavaScript language entirely in Java.

Rhino solves the problem of executing JavaScript code within Java applications and environments where a native JavaScript runtime is unavailable or impractical. It parses and interprets JavaScript source code, compiling it to Java bytecode for execution on the Java Virtual Machine. This approach allows developers to embed dynamic scripting capabilities directly into Java programs without external dependencies.

Rhino suits projects that need to execute untrusted or user-provided scripts within a Java application, integrate JavaScript logic into Java backends, or support scripting in Java-based tools and frameworks. It is particularly valuable for applications requiring a sandboxed execution environment where JavaScript can interact with Java objects and methods. The tool provides a compatibility table documenting support for ES6 and later JavaScript features, allowing developers to assess whether their target language features are available.

The project maintains a regular release cadence with multiple releases per year. Development activity shows consistent engagement with both new features and maintenance updates across the codebase. The project requires Java 17 or higher to run and Java 21 or higher to build, with Java 25 recommended for development.