Scala.js vs Emscripten: What are the differences?

Scala.js: The Scala to JavaScript compiler *. It is a safer way to build robust front-end web applications. With it, typos and type-errors are immediately caught and shown to you in your editor, without even needing to compile your code. Refactor any field or method with ease, with the confidence that if you mess it up the editor will tell you immediately; *Emscripten:** An Open Source LLVM to JavaScript compiler. This allows applications and libraries originally designed to run as standard executables to be integrated into client side web applications.

Scala.js and Emscripten belong to "JavaScript Compilers" category of the tech stack.

Some of the features offered by Scala.js are:

• Strong typing
• optimizes your Scala code into highly efficient JavaScript
• use any JavaScript library right from your Scala.js code

On the other hand, Emscripten provides the following key features:

• Compile C and C++ code into JavaScript
• Compile any other code that can be translated into LLVM bitcode into JavaScript
• Compile the C/C++ runtimes of other languages into JavaScript

Scala.js and Emscripten are both open source tools. It seems that Emscripten with 17.9K GitHub stars and 2.12K forks on GitHub has more adoption than Scala.js with 3.74K GitHub stars and 332 GitHub forks.