Flow
A static type checker for JavaScript
Flow is a static type checker for JavaScript. It was designed to help improve code quality and developer productivity. It does this through several smart capabilities. First, it identifies problems as you code, so you no longer have to waste time guessing and checking again and again. Second, it understands your code and makes its knowledge available, allowing you to build other smart tools on top of it. Third, it helps you refactor safely so you can focus on the changes you want to make...