How do I get value from ACE editor?

Question

I am using ACE editor for the first time. I have the below questions related to it.

1. How do I find the instance of ACE editor on the page? I don't want to maintain a global variable which will hold the editor instance. I need to find its instance on demand.

2. How to get and set its value?

I am open for suggestions for any better editor than ACE editor which will support almost all types of language/markup/css etc and highly integrated with jQuery.