Question

I had some pseudoclasses that shared a large part of their initialization. I decided to take this initialization out and create a base class, from which they’ll inherit.

function BaseClass(param1, param2) {
    ...
}

function SubClassA(param1) {
    ...
}

function SubClassB(param1) {
    ...
}

I want SubClass1 and SubClass2 to inherit from BaseClass in the following manner:

SubClassA(param1) constructor calls BaseClass(param1, "I am A.")

SubClassB(param1) constructor calls BaseClass(param1, "I am B.")

so BaseClass adds some properties to them. Then both subclasses do some initialization of their own.

Now I can’t just do SubClassA.prototype = new BaseClass(), because I want the super constructor to take parameters. How to do this elegantly?

Answer 1

function SubClassA(param1) {
    BaseClass.call(this, param1, "I Am A.");
}

function SubClassB(param1) {
    BaseClass.call(this, param1, "I Am B.");
}

When you do a new SubClassA(param1) or new SubClassB(param1) base constructor will be called with appropriate parameters.

Also, there are other ways than SubClassA.prototype = new BaseClass() to define base class. You can check this question for some details. (Disclaimer: The question was asked by me.)