Why I can add into Set the same arrays?

Question

I can add into Set exactly the same arrays, but Set mustn't add elements that already exist in this Set. Set must store only unique values. But Why am I able to add these?

let s = new Set();
s.add([1]);
s.add([1]);
s.add([1]);

console.log(s); //Set(3) {Array(1), Array(1), Array(1)}

what language and framework are you using? – Tom Elias Dec 23 '21 at 15:45 — Tom Elias, Dec 23 '21 at 15:45
@scrappedcola, yes, exactly, thanks! – SerhiyAndryeyev Dec 23 '21 at 16:07 — SerhiyAndryeyev, Dec 23 '21 at 16:07

score 0 · Accepted Answer · answered Dec 23 '21 at 15:59

The problem with the Set object in ES6 is that the equality check is based on comparing the actual reference of inserted objects. Thus, when inserting multiple Arrays with the exact same content, it treats them as non-identical as the underlying object reference differs. Same goes for other objects. Primitives on the other hand are compared based on their values.

Why I can add into Set the same arrays?

1 Answers1