Q:

Is it possible to create a property from another property within the same prototype object?

New to coding:
I'm trying to do something like this in Javascript:
function Calculator(a,b){
 this.a=a;
 this.b=b;
 this.c=a*b;
 this.d=c;
}

var myTiCalc = new Calculator(1,2);
alert(myTiCalc.d);

So that it prints "d" in an alert box. However I keep getting a "Nan" in the alert. 
Appreciate your expertise!

A:

function Calculator(a,b){
 this.a=a;
 this.b=b;
 this.c=a*b;
 this.d=this.c;
}

var myTiCalc = new Calculator(1,2);
alert(myTiCalc.d);

In the line #5 you put this.d=c; instead of this.d=this.c. Variable c was not defined anywhere. What I think you need is to assign property c to d of the Calculator object, so you need to call it with the this keyword.

