Last month I had the opportunity to speak at the London Node User Group about an exciting technology called Flow. You can find the video below, along with the abstract and slides:


Flow is a static type checker for JavaScript (an otherwise dynamically-typed language). You can think of it as a productivity tool that catches common errors before they run.

Take the infamous “Undefined is not a function” error as an example. When writing vanilla JavaScript, you would have to wait until runtime to receive this arduous error. Flow – on the other hand – integrates with your favorite editor and analyzes the correctness of your code as you write it. If you were to reference a non-existent function, Flow would not only tell you immediately but also provide additional context that makes the error easier to fix.

Whilst Flow is predominantly used with front-end technologies like React, I have been using it with great success for my Node.js projects and in this talk, I not only show you how to get up and running with Flow, I’ll also share my experience with you.