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javascripttypescriptweak-references

Difference between WeakSet<T> and Set<Weakref<T>>


I was recently wondering if there is any drawback for Set<Weakref<T>> over WeakSet<T>.

Pros:

  • The set is iterable

Cons:

  • The set must be filtered from no longer valid references

Am I missing something or is this almost a win-win situation? Would the Set<Weakref<T>> version prevent the garbage collector from collecting?


Solution

  • What you missed:

    WeakSets are collections of objects only. They cannot contain arbitrary values of any type, as Sets can.

    The number of objects or their traversal order is immaterial, so a WeakSet is more suitable (and performant) than a Set for tracking object references, especially if a very large number of objects is involved.

    MDN source

    Set<Weakref<T>> will not prevent GC. Also note that WeakRef is not supported in Opera but WeakSet is.