Bazel is part of a general effort called ABC(Angular BootCamp) from Google to improve building and testing on Angular apps. This was possible because some very talented engineers developed the tooling needed to turn JavaScript into an enterprise development platform. We created a typed variant of JavaScript, called Closure, with a standard library, the Closure Library, and the Closure Compiler, which is a type checker, ES2015-transpiler, optimizer, bundler, minifier, all in a single command.