One of the most important building blocks in any JavaScript runtime is the eventloop which enables developers to write performant code, even single-threaded. But many developers do not look into how it works because it looks really complicated and hard to understand. In this talk we will discover how the eventloop works, what the differences there are between micro- and macrotasks, how one can use them to ones advantage and how they work with Promises, Timer-Events and Web-Apis. All easily understandable and done in Live-Coding.