title: Overriding backbone model prototype vs extending model
body: <p>I'm new to Backbone.js and in my recent project I need a custom validation mechanism for models. I see two ways I could do that.</p>
  
  <ol>
  <li><p>Extending the Backbone.Model.prototype</p>
  
  <p>_.extend(Backbone.Model.prototype, {
       ...
    });</p></li>
  <li><p>Creating custom model that inherit from Backbone model</p>
  
  <p>MyApp.Model = Backbone.Model.extend({ ... });</p></li>
  </ol>
  
  <p>I quite unsure which one is a good approach in this case. I'm aware that overriding prototype is not good for native objects but will that applies to backbone model prototype as well? What kind of problems I'll face if I go with the first approach?</p>