Object-Oriented JavaScript - Third Edition

Using a mix of prototypal inheritance and copying properties

When you use inheritance, you will most likely want to take an already existing functionality and then build upon it. This means creating a new object by inheriting from an existing object and then adding additional methods and properties. You can do this with one function call using a combination of the last two approaches just discussed.

You can:

• Use prototypal inheritance to use an existing object as a prototype of a new one
• Copy all the properties of another object into the newly created one:

      function objectPlus(o, stuff) { 
        var n; 
        function F() {} 
        F.prototype = o; 
        n = new F(); 
        n.uber = o; 
     
       for (var i in stuff) { 
          n[i] = stuff[i]; 
          } 
        return n; 
      } 
  

This function takes an object o to inherit ...