[jQuery] Two dimensional arrays and $.post

Hi list,

I need to dynamically create an associative array in jquery, then pass
it to a php script for processing (using the $.post method), in order
to receive a value of some sort.

The array is generated every time the user performs a change in a
select list element, and is of the following structure:
myArray = [ ID => value, ID => value, ..., ID => value]

My questions:
- How can I define an associative array?
- How can I pass it on a php script using $.post?

Thanks in advance!

St