# mozilla/rhino

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

Repository: https://github.com/mozilla/rhino
Canonical: https://ross.abutalabs.com/products/rhino
Homepage: https://rhino.github.io
Language: JavaScript
License: NOASSERTION
License Family: other
Last push: 2026-08-25T02:50:38+00:00

## Health v2 (maintenance only)
Score: 89/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 71, longevity 100
- inputs: {"age_days": 5592, "days_push": 8, "days_rel": 199, "gap_med": 19, "n_releases_24m": 6}
- flags: no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 4620, forks 927 (observed 2026-08-28T04:08:55.152251+00:00)

## What it is
Rhino is an open-source implementation of JavaScript written entirely in Java, maintained by Mozilla. It is typically embedded into Java applications to provide scripting capabilities and serves as the default scripting engine in J2SE 6.

## Use cases
- embed a JavaScript scripting engine in a Java application
- evaluate JavaScript expressions from Java code
- run JavaScript on the JVM without Node.js
- let end users script or extend a Java application
- execute JS-based configuration or business rules inside a Java server

## When to choose
- you need to run or evaluate JavaScript inside a JVM application
- you want to expose user-facing scripting in Java software
- you need a pure-Java JS engine with no native dependencies
- you are maintaining legacy Java apps that rely on the javax.scripting JS engine

## When to avoid
- you need modern Node.js APIs, npm packages, or the latest ECMAScript features
- you need maximum JavaScript execution performance (V8-based engines are faster)
- you are building a browser or server-side JS stack rather than embedding scripting in Java

## Facets
- artifact type: library
- maturity: active
- function: interpreter, programming-language, cli, developer-tools
- domain: programming-languages, developer-tools, cross-platform
- platform: jvm, cli, cross-platform
- tags: javascript-engine, scripting, embedding, es6, mozilla

## Member repositories
- mozilla/rhino (main) score 89

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:55.152251+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T18:19:39.517867+00:00, confidence not recorded.
  - readme: https://github.com/mozilla/rhino (fetched 2026-08-28T04:08:55.152251+00:00, sha be20b02f81a7)
  - homepage: https://rhino.github.io (fetched 2026-08-29T09:04:39.424345+00:00, sha ca1390478504)
- Data as of 2026-08-30T08:39:29.467469+00:00.