[jQuery] construct a MAP

Hi,
I am using the $.post() function, the second parameter is a Map which
is Key/value pairs that will be sent to the server. how do I create a
map to use in $.post().
I can't find any information about map for javascript may be it's not
supported? and this map is in jquery only? is this correct way to make
a map?
a_map = {name:'james', age:'27', location:'HK'}
Thanks
james