JavaScript WeakSet
JavaScript WeakSet
A JavaScript WeakSet is similar to a normal Set, but with some important differences. It stores only objects (not numbers, strings, or other primitives), and it allows objects to be garbage-collected when no longer referenced.
WeakSets are useful when you want to track objects temporarily without preventing them from being removed from memory.
Key Characteristics of WeakSet
| Feature | WeakSet | Set |
|---|---|---|
| Stores only objects | Yes | No (can store any type) |
| Allows garbage collection | Yes | No |
| Iterable | No | Yes |
| Methods supported | add(), has(), delete() | Many |
| Size property | No | Yes |
Creating a WeakSet
Adding Values (Only Objects Allowed)
Removing Values
Garbage Collection Example
If an object stored in WeakSet no longer has references elsewhere, it is removed automatically from memory.
Limitations of WeakSet
WeakSet is not iterable, so you cannot loop through it:
When to Use WeakSet?
Use it when you want to track objects without preventing memory cleanup, such as:
Caching objects temporarily
Marking objects as processed
Tracking DOM element states
Practical Example: Tracking DOM Elements
Summary
| Action | WeakSet Support |
|---|---|
| Add items | add() |
| Remove items | delete() |
| Check item exists | has() |
| Iterate items | No |
| Primitive values allowed | No |
