Please add .pop()

[Ginden]

From @tabatkins on January 23, 2018 22:16

Popping from a Set/Map is actually very useful, regardless of whether there's a direction/ordering or not. The semantics are just "remove one arbitrary value from the set and give it to me", which is annoyingly clumsy to implement by hand.

I've used .pop() in Python several times, and felt the lack of it in JS projects.

Copied from original issue: tc39/proposal-set-methods#18

[ljharb]

@tabatkins Would this need to pull the last one? could it pull the first?

[tabatkins]

Don't care; authors should be treating Sets as unordered, anyway, and accept the orderedness as an accidental implementation detail we're forced to bake in. ^_^

[zloirock]

For me makes sense an equal of .shift - getting and removing the first element from entries chain. JS Set at this moment is ordered collection, adding a getter of the last element of the collection with O(1) complexity is adding a new fundamental conception to JS collections, not just sugar for available at this moment features and looks redundant.

[ljharb]

So, some kind of sugar like:

unshift() {
  for (const item of this) {
    this.delete(item);
    return item;
  }
}

?

[zloirock]

Yep. One moment - I made a typo, I mean .shift.

[tabatkins]

Whether we name the function unshift() or pop(), we should probably match the semantic of the same function on Arrays, and return either the first or last accordingly.

So yeah, if we want to return the first item, in accordance with that simple desugaring, the function should be called unshift() I think.