> $.each(['a', 'b', 'c'], function(i,v) {console.log([i,v])})
[0, "a"]
[1, "b"]
[2, "c"]
> $.map(['a', 'b', 'c'], function(i,v) {console.log([i,v])})
["a", 0]
["b", 1]
["c", 2]