[jQuery] HELP: how to browser cache json request?

[wgordonw1]

I cannot figure out how to get my json file to be cached by the
browser when I download it with an ajax request.  I have tried two
different methods:

method one:

$.ajax({
                type: "GET",
                url: "long_url.json",
                dataType: "json",
                cache: true,
                ifModified: true,
                error: function(XMLHttpRequest, textStatus, errorThrown){
                                        alert('ERROR! \n XMLHttpRequest: ' + 
XMLHttpRequest + '\n
textStatus: ' + textStatus + '\n errorThrown: ' + errorThrown);
                                },
                success: function(data, textStatus){
                                        alert('SUCCESS! \n data: ' + data + '\n 
textStatus: ' +
textStatus);
                                },
                complete: function(XMLHttpRequest, textStatus){
                                        alert('COMPLETE! \n XMLHttpRequest: ' + 
XMLHttpRequest + '\n
textStatus: ' + textStatus);
                                }
        });


method two:

        $.ajaxSetup({
          type: "GET",
          cache: true,
          ifModified: true
        });

        $.getJSON("long_url.json", function(data, textStatus){
                alert('COMPLETE! \n data: ' + data + '\n textStatus: ' +
textStatus);
        });


In both cases, each time I load the page I have to download a copy of
the ajax request before it will send the correct last-modified
headers.  It first sends the default 1970 date.  After I initiate the
first request, all subsequent requests return proper 304 not modified
responses.  I am guessing this is because my file isn't being cached
by the browser.  How do I get the browser to cache my file?  The json
file that I am loading will not change very often and it is fairly
large.  I do not want my users to have to download it unless they have
a stale copy.