JavaScript Weakmap_weakset Guide
WeakMap and WeakSet hold weak references to objects, allowing garbage collection when no other references exist. The guide walks through Weak Collections. WeakMap: keys must be objects, no size/iteration, auto-GC. Use: private data per object, DOM node metadata, caching computed results. WeakSet: objects only, no iteration, auto-GC. Use: marking objects (visited, processed), DOM node tracking without preventing GC. Unlike Map/Set: no .size, no .keys(), no .values(), no .entries(), no .clear(). The guide is organized into 1 sections that build on each other, each pairing a prose explanation with runnable code. Related guides: Arrays, Strings, Numbers, Math, Date. This is one of 145 JavaScript guides on JS Reference — see the full list on the guides page. Practice what you learn in the JavaScript playground, and look up any unfamiliar term in the JavaScript glossary.