function isDefined(obj) {
		return typeof obj !== 'undefined';
	}
This class mimics most of the jQuery API:

This is whats currently implemented:
- Utility functions
- DOM traversial
- DOM manipulation
- Event binding

This is not currently implemented:
- Dimension
- Ajax
- Animation
- Advanced chaining

@example
var $ = tinymce.dom.DomQuery;
$('p').attr('attr', 'value').addClass('class');

@class tinymce.dom.DomQuery