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Scala.js

Ch 245.5of 28 Code Transpilers
  1. 1Runs onAPI, Linux, Mac, Web, Windows
  2. 2CostsFree plan
  3. 3Intermediate outputYes
  4. 4CLI accessYes
  5. 5API accessYes
  6. 6Conversion modeboth
6 lines stated Written from the maker's own pages: scala-js.org
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The Scala.js homepage

Overview

Scala.js is ranked #24 of 28 in code transpilers on Specifiction. It runs on API, Linux, macOS, Web, Windows. There is a free plan.

Scala.js plans and pricing

All plans
Scala.js Free Scala to JavaScript compiler · managed through a Scala build tool scala-js.org · 4 Oct 2026

Compared on code transpilers

Intermediate output
Yesscala-js.org
CLI access
Yesscala-js.org
API access
Yesscala-js.org
Conversion mode
bothscala-js.org

Facts

Purpose
Scala.js is a Scala to JavaScript compiler for building applications that run in browsers, Node.js, and serverless environments.scala-js.org · 4 Oct 2026
Correctness
The site says Scala.js uses strong typing to catch mistakes such as mixing strings and numbers or calling methods with typos.scala-js.org · 4 Oct 2026
Performance
The site describes incremental compilation with 1–2 second turnaround and generated JavaScript starting at 45 kB gzipped for a full application.scala-js.org · 4 Oct 2026
JavaScript interoperability
Scala.js can use JavaScript libraries and interact with JavaScript APIs, with either statically or dynamically typed access.scala-js.org · 4 Oct 2026
Library ecosystem
The libraries page lists facades and integrations for libraries including React, Angular, Vue, Three.js, and Chart.js.scala-js.org · 4 Oct 2026
Build tools
The documentation names sbt, scala-cli, Mill, and Gradle with a Scala.js plugin as supported build tool options.scala-js.org · 4 Oct 2026
Development setup
The tutorials list Scala development tools and Node.js as prerequisites and recommend VS Code with the Metals extension.scala-js.org · 4 Oct 2026
Output targets
The June 2026 release announcement says WebAssembly support is stable; the homepage describes browser, Node.js, and serverless apps.scala-js.org · 4 Oct 2026
Editor support
The homepage says editor support catches typos and type errors and provides inline method, argument, return type, and documentation information.scala-js.org · 4 Oct 2026
License
The project repository states that Scala.js is distributed under the Apache License Version 2.0.github.com · 4 Oct 2026
Support
The documentation directs users to the community for help, including Discord and Stack Overflow.scala-js.org · 4 Oct 2026
Compatibility note
The 1.22.0 release announcement says the release is not entirely backward source compatible with 1.21.x.scala-js.org · 4 Oct 2026

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