title: Prototype inheritance, why an instance and not the prototype?
body: <p>I've always wondered since i learned about prototype inheritance why you push an instance of the parent class into the child prototype and not the prototype itself?</p>
  
  <pre><code>var Animal = function(type){
      this.type = type;
  }
  Animal.prototype.getType = function(){
      return this.type;
  }
  var Cat = function(options){
      this.breed = options.breed;
  }
  
  //Inheritance
  Cat.prototype = new Animal('Cat');
  </code></pre>
  
  <p>Why not do the inheritance like this?</p>
  
  <pre><code>Cat.prototype = Animal.prototype;
  </code></pre>
  
  <p>My guess is that with only inheriting the prototype you aren't including the properties created in the constructor (this.type) but I'm not entirely sure. Anyone want to enlighten me?</p>
  
  <p>But isn't putting an instance into the child class prototype putting all constructor-defined properties in the prototype too and thus introducing possible pitfalls? I'm thinking about the fact that the prototype properties are shared among all instances of a class unless they are defined in the constructor.</p>