Brython vs Scala.js

Brython has no write-up on Specifiction yet; its figures are above.

Scala.js is a Scala-to-JavaScript compiler for building applications that run in browsers, Node.js, and serverless environments. The project also states that WebAssembly support is stable. Scala's strong typing can catch mistakes such as mixing strings and numbers or using misspelled method names, while editor support can flag type errors and show inline details about methods, arguments, return types, and documentation. The project describes incremental compilation with a 1–2 second turnaround; generated JavaScript for a full application starts at 45 kB gzipped. Scala.js can use JavaScript libraries and APIs through statically or dynamically typed access. Listed library integrations include React, Angular, Vue, Three.js, and Chart.js. Build tool options include sbt, scala-cli, Mill, and Gradle with a Scala.js plugin. Tutorials list Scala development tools and Node.js as prerequisites and recommend VS Code with Metals. Scala.js is free and distributed under the Apache License 2.0. Documentation points users to community support through Discord and Stack Overflow. The 1.22.0 release is not entirely backward source compatible with 1.21.x.