# scala-js/scala-js

Scala.js, the Scala to JavaScript compiler

Repository: https://github.com/scala-js/scala-js
Canonical: https://ross.abutalabs.com/products/scala-js
Homepage: https://www.scala-js.org/
Language: Scala
License: Apache-2.0
License Family: permissive
Topics: scala, javascript-compiler, language, compiler
Last push: 2026-08-15T18:05:40+00:00

## Health v2 (maintenance only)
Score: 91/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 97, release rhythm 77, longevity 100
- inputs: {"age_days": 4944, "days_push": 18, "days_rel": 74, "gap_med": 88, "n_releases_24m": 10}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 4710, forks 408 (observed 2026-08-28T04:08:57.388812+00:00)

## What it is
Scala.js is a compiler that translates Scala code into efficient JavaScript, letting developers write type-safe applications for browsers, Node.js, and serverless environments. It provides full interoperability with JavaScript libraries and ecosystems while retaining Scala's strong static typing.

## Use cases
- compile scala code to javascript
- build type-safe frontend apps in scala
- share code between jvm backend and browser frontend
- use react from scala with static typing
- develop serverless functions in scala
- avoid javascript type errors with strong typing

## When to choose
- your team knows Scala and wants to target the browser or Node.js
- you want strong static typing and editor tooling over JavaScript
- you need to share business logic between JVM and JavaScript codebases

## When to avoid
- your team is JavaScript/TypeScript-first with no Scala experience
- you need tiny bundle sizes below what optimized Scala.js output provides
- you rely on JS tooling or libraries without good interop needs

## Facets
- artifact type: cli-tool
- maturity: stable
- function: compiler, programming-language, type-system, developer-tools
- domain: compilers, programming-languages, web-development, frontend, cross-platform
- platform: browser, cross-platform, jvm
- tags: scala, scala-to-javascript, transpiler, strong-typing, javascript-interop, compiler, nodejs, web-server

## Member repositories
- scala-js/scala-js (main) score 91

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:57.388812+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 2026-08-30T08:31:24.767728+00:00, confidence not recorded.
  - readme: https://github.com/scala-js/scala-js (fetched 2026-08-28T04:08:57.388812+00:00, sha e83838e6eb84)
  - homepage: https://www.scala-js.org/ (fetched 2026-08-29T09:03:00.216483+00:00, sha 8199892f27ca)
  - site_page: https://www.scala-js.org/doc (fetched 2026-08-29T09:03:00.225545+00:00, sha 58e6e6e4cf62)
- Data as of 2026-08-30T08:39:29.467469+00:00.