SO fiddle

Test Fiddle mainly for SO Questions

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/overcast/jquery-ui.css">
<div>Click me!</div>

JavaScript

var click1 = function() {
  this.setStyle('background', 'red');
};

$$('div').addEvent('click', click1);