Go with the
FlowType

Why types?

Want to know if your program is correct before you ship it to the browser? Types can help you know if your code integrates well together. Want more insight into developer intent when reading code? Types can help expose that better. Want more feedback while your coding for a more confident development experience? Typing and compiling your code can help with that too.

Learn more

Why Flow?

Flow, or Flowtype, is a strong, static typing system for JavaScript. Keep your language, your toolchain, your talent pool, and get some great benefits. Add types in your JavaScript project where you want or need them, gradually.

Official docs

The Project

To demonstrate Flow, we make a choose your own adventure game, where the narrative is chosen by the reader over time. It's a silly tale of galactic treachery and loyal friends. We start with an empty directory and end with a small, fully-flowtyped web application.

Types You'll Learn

any
object
primitive
array
function
mixed
module
maybe
variable
inference
type alias
generic
class
interface
intersection
tuple
literal
type cast
union
libdef