JavaScript Weak_refs_basics Guide
WeakRef and FinalizationRegistry provide low-level memory management for advanced caching and resource cleanup scenarios. The guide walks through WeakRef. `new WeakRef(obj)` — weak reference (doesn't prevent GC). `.deref()` — returns object or undefined if GCed. Use for: large object caches (images, data), DOM-to-JS mappings without preventing cleanup. Uncommon — most apps don't need it. 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.