One of the "neat" things in Javascript is you are able to dynamically add or change methods of a class and automatically update every instance of that class. Some of the things I usually find useful are adding to the String class, like so:
Posts Tagged As "php"
Persistent Static Variables Across Instances in PHP
Wait, What? Yeah that's what I thought too. Still no Idea what I'm talking about? Well, let's take a look at the following code. Let's call it "fred".