javascript check if set contains

const mySet = new Set();

// Add value to set
mySet.add(15);

console.log(mySet.has(33)) // expected output: false
cosole.log(mySet.has(15)) // expected output: truevar mySet = new Set();
mySet.add('foo');

mySet.has('foo');  // returns true
mySet.has('bar');  // returns false

var set1 = new Set();
var obj1 = {'key1': 1};
set1.add(obj1);

set1.has(obj1);        // returns true
set1.has({'key1': 1}); // returns false because they are different object references
set1.add({'key1': 1}); // now set1 contains 2 entries