IconVault's WeakRef & GC visualizer lets you run real garbage-collection experiments: allocate objects of a chosen size, hold them only through WeakRef, and register them with a FinalizationRegistry. Drop the strong references, trigger a GC cycle, and watch liveness checks flip from alive to reclaimed while finalization callbacks stream into the log with timestamps. It is free and runs fully in your browser.

Because JavaScript exposes no API to force collection, the lab teaches the honest workflow: the DevTools Memory tab's collect-garbage button, Chrome's `--js-flags=--expose-gc` flag, and a memory-pressure button that genuinely allocates and discards large temporaries to encourage a cycle. You will see why `deref()` returning `undefined` is the only safe liveness test and why finalization callbacks must never be used for critical cleanup.