Chapter XXIV · Advanced Concepts
WeakSet
A `WeakSet` is a collection containing only unique object references held weakly, making them eligible for garbage collection.
01 How It Works
Think of a temporary visitor guest check-in list that clears out once visitors leave.
WeakSets are not iterable and do not prevent their stored object items from being garbage collected.
example.js
const ws = new WeakSet();
let obj = { active: true };
ws.add(obj);
console.log(ws.has(obj)); // true1. Initialize a `WeakSet` instance.
2. Add object references using `.add(obj)`.
3. Check existence with `.has(obj)`.
02 Practical Example
Here is how you might see this concept applied in real-world code:
practical.js
const visitedNodes = new WeakSet();
function markVisited(node) {
visitedNodes.add(node);
}Key Takeaway
WeakSets store object collections weakly without preventing garbage collection.