[jQuery] Which attributes of a file input pass to a .php or .aspx using $.getJSON() ?

[jQuery] Which attributes of a file input pass to a .php or .aspx using $.getJSON() ?


Hi all, i'm using jQuery to pass a file to a .php or .aspx page using
$.getJSON() function.
My problem is: how can i pass all the input file data to that page?
Which attributes of the input file have i to pass?
I think that i have to pass the name of the file ( and here ok, i can
get it with .attr('value') ), than the real data of the file input,
and this is the real problem couse i don't know how to retrive it...
Can someone help me giving me some answer, hints or tutorials?