Object-Oriented JavaScript - Third Edition

Copying properties

Now, let's try a slightly different approach. Since inheritance is all about reusing code, can you simply copy the properties you like from one object to another? Or from a parent to a child? Keeping the same interface as the preceding extend() function, you can create a extend2()function, which takes two constructor functions and copies all the properties from the parent's prototype to the child's prototype. This will, of course, carry over methods too, as methods are just properties that happen to be functions:

    function extend2(Child, Parent) { 
      var p = Parent.prototype; 
      var c = Child.prototype; 
      for (var i in p) { 
        c[i] = p[i]; 
      } 
      c.uber = p; 
    } 

As you can see, a simple loop through the properties is all it takes. As with the ...