javascript - Get last value inserted into a Set

Question

The MDN documentation for Set says that JavaScript Set objects retain insertion order of elements:

Set objects are collections of values, you can iterate its elements in insertion order.

Is there a way to get the last item inserted into a Set object?

var s = new Set();
s.add("Alpha");
s.add("Zeta");
s.add("Beta");

console.log(getLastItem(s)); // prints "Beta"

Edit

It is possible to implement a Linked Set datastructure container class that has the same interface as Set and has the desired capability. See my answer below.

question from:https://stackoverflow.com/questions/34583643/get-last-value-inserted-into-a-set

Answer 1

I was not able to find any method to get last value inserted in set from ECMA 2015 Specification, may be they never intended such a method, but you can do something like:

const a = new Set([1, 2, 3]);
a.add(10);
const lastValue = Array.from(a).pop();

Edit:

on second thought, a space efficient solution might be:

function getLastValue(set){
  let value;
  for(value of set);
  return value;
}

const a = new Set([1, 2, 3]);
a.add(10);
console.log('last value: ', getLastValue(a));