Union

The union method returns a set containing all the unique elements from the set that the method is called on, as well as the set that was provided as a parameter:

let evenOrTriangularNumbers = evenNumbers.union(triangularNumbers) 
  // 2,4,6,8,10,1,3,unordered 

The following diagram depicts the Union of Set A and Set B:

Figure 2.2 – Union of sets