Combining the use of parent class constructors for initialization and prototypes for inheritance provides benefits with regard to inheritance, initialization and method overridding.
Clearly identifies parent class.
Easy initialization of properties inherited from parent class.
Clear inheritance chain available from instanceof
Easy to call overridden methods from parent class
The initialization of the myChildClass prototype is not deferred in this most common use
of prototype based inheritance. This required that the parent class be instantiated while
the page was loading but before the DIV used to contain messages was fully
ready.
Initialization of prototype from a parent class can lead to dependencies in the child class on the arguments used to construct the parent class instance used as a prototype. For example, an immediate property in the parent class which becomes a prototype property in the child class.
As you can see in the example, the name property of
myChildClass was prototyped to the value defined in the call to create the
instance of myParentClass used as myChildClass's prototype.