Closure Compiler is a JavaScript optimizing compiler. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls. It is used in many of Google's JavaScript apps, including Gmail, Google Web Search, Google Maps, and Google Docs.

Scala.js linker

JSCover is a tool that measures code coverage for JavaScript programs.

Charba - J2CL and GWT charts library based on CHART.JS

Preprocess (combine, transpile, minimize) JavaScript with closure compiler.

WicketStuff Closure Compiler Integration