Set.prototype.size

The size accessor property returns the number of (unique) elements in a Set object.

The 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.

var mySet = new Set();
mySet.add(1);
mySet.add(5);
mySet.add('some text')

mySet.size; // 3

• Set