Simply adding a type system to an existing JavaScript codebase using Flow or TypeScript can help document your code and avoid bugs. While you can treat types as simply an additional layer on top of the code you would normally write, to get the most out of a type system it's worth approaching it as a new language with its own idioms and patterns.
To understand the real power of these new tools we'll explore patterns from other strongly typed languages like Rust, Elm, and OCaml and see how we can apply them in our JavaScript codebases. Learn how to leverage the type system to help you refactor your code, ship changes with confidence, and never see `undefined is not a function ever again.
