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Like WeekMap but consists of values only (WeakSet = Set + Weakness - Iterable)
- Not iterable
- Values must be reference types
- Garbage collected
// has only .add, .has, .delete methods
const set = new WeakSet();
set.add({});
set.add(new Date());
set.add(1); // throws an exception
// or:
const newSet = new WeakSet([() => 'one', [], new Date()]);Usage: (I've found only one example)
const fooInstances = new WeakSet();
class Foo
{
constructor()
{
fooInstances.add(this);
}
method()
{
// check that prototype isn't faked
if (!fooInstances.has(this)) { throw new Error('Foo.prototype.method called on incompatible object.'); }
}
}