MooTools Selectors Using $$
MooTools Core has a bundled method $$ – also referred to as dollars – that selects and extends DOM elements. This is a very powerful function and will allow you to select 1 or more DOM elements using some pretty clever tricks.
When you call $$(), it will return an array of all the elements found matching your criteria. In addition to some CSS3 selectors you might have already seen, MooTools implements some custom ones that are very helpful as well.

