Sorting a JavaScript object by property name

I've been looking for a while and want a way to sort a Javascript object like this:

{    method: 'artist.getInfo',    artist: 'Green Day',    format: 'json',    api_key: 'fa3af76b9396d0091c9c41ebe3c63716'}

and sort is alphabetically by name to get:

{    api_key: 'fa3af76b9396d0091c9c41ebe3c63716',    artist: 'Green Day',    format: 'json',    method: 'artist.getInfo'}

I can't find any code that will do this. Can anyone give me some help?