console.log(today.getDay()) // prints 1 assuming there was a setDay, and you invoke: today.setDay(3) should today now be: 21/9/2016 or 14/9/2016 or 19/10/201

console.log(today.getDay()) // prints 1 assuming there was a setDay, and you invoke: today.setDay(3) should today now be: 21/9/2016 or 14/9/2016 or 19/10/2016 or 19/9/2040 or ... ? I think you can see that unlike the other setters, setDay would not have an "obvious" implementation.