Garbage Collection (GC) in JavaScript is supposed to simplify and automate memory management. But it turns out that there are various scenarios where GC can get in the way, and avoiding resource leaks becomes challenging. In order to overcome such issues, the ECMAScript standard includes WeakMap and WeakSet. Also, Chrome recently added support for WeakRef and FinalizationRegistry, which will soon be part of the standard as well. In this presentation I explain what these are, why they're needed, and provide concrete usage examples and best practices.