Compare two arrays as sets

A multi-select gives you an array of ids. Deciding whether to refetch means asking whether the selection really changed — and ["a", "b"] versus ["b", "a"] is not a change, nor is ["a", "a", "b"] versus ["a", "b"].

Implement sameSet(a, b). Return true when the two arrays contain exactly the same distinct values, ignoring order and ignoring how many times each value appears, and false otherwise. Values are compared the way a Set compares them, so NaN matches NaN but 1 does not match "1". Two empty arrays are the same set. An empty array and a non-empty one are not. Never modify either input.

sameSet([1, 2, 3], [3, 2, 1]);   // true — order does not matter
sameSet([1, 1, 2], [2, 1, 1, 1]); // true — duplicates do not matter

sameSet([1, 2], [1, 3]);          // false — different distinct values
sameSet([NaN], [NaN]);            // true — Set-style equality matches NaN
sameSet([1], ["1"]);              // false — Set-style equality keeps types distinct