title: How to add my own methods to HTMLElement object?
body: <p>For example for <code>this.parentNode</code> I would like to just write <code>this.p</code> or instead of
  <code>document.getElementById('someid')</code> just write <code>document.g('someid')</code>. Of course that are simple examples, I just want to know what is the correct way to do it.</p>
  
  <p>(I know I can use jQuery or Prototype, but I'd like to learn how it is really done in JS)</p>