The size accessor property of Set instances returns the number of (unique) elements in this set.
const set = new Set();
const object = {};
set.add(42);
set.add("forty two");
set.add("forty two");
set.add(object);
console.log(set.size);
// Expected output: 3The value of size is an integer representing how many entries the Set object has. A set accessor function for size is undefined; you cannot change this property.
const mySet = new Set();
mySet.add(1);
mySet.add(5);
mySet.add("some text");
console.log(mySet.size); // 3