Wierd behaviour of constructor property of an object

Question

In the following code, why is \'scotty.constructor\' set to \'Dog\' function ? How is the constructor property of an object set in general ? Is it set to the function that creat

Answer 1

Object don't have an own constructor property, it's taken from their protos. So, without this line:

ShowDog.prototype = new Dog();

the inheritance diagram would be

Once you assign new Dog to the prototype (thus discarding its current value), the picture becomes:

and the constructor value (Dog) is taken from scotty.__proto__.__proto__

To make inheritance work as intended, you have to assign the constructor manually:

ShowDog.prototype = new Dog()
ShowDog.prototype.constructor = ShowDog

which yields the following diagram: