Question

Anyone have any idea why this isn’t working?

$(function(){
    console.log('ready');
    $.ajax({
        dataType : 'jsonp',
        jsonp : 'js',
        url : 'http://monitor.302br.net/MonitorScoreServlet',
        beforeSend : function(jqXHR, settings) {
            console.info('in beforeSend');
            console.log(jqXHR, settings);
        },
        error : function(jqXHR, textStatus, errorThrown) {
            console.info('in error');
            console.log(jqXHR, textStatus, errorThrown);
        },
        complete : function(jqXHR, textStatus) {
            console.info('in complete');
            console.log(jqXHR, textStatus);
        },
        success: function(data, textStatus, jqXHR){
            console.info('in success');
            console.log(data, textStatus, jqXHR);
        }
    }); 
}); 

This was working till recently. The beforeSend handler never fires, but you can see the ajax call being made in firebug, and if you go to the url, it seems to return acceptably formatted results (the same results as before):

http://monitor.302br.net/MonitorScoreServlet?js=jsonp1298046640938
text/javascript:

(84.3);

If I comment out the url, the beforeSend fires, but of course, there’s no url….

Any ideas?

Answer 1

Ok, I feel dumb. Here’s what I think happened: the server used to be set up to take the js param as a callback function. So a url like:

http://monitor.302br.net/MonitorScoreServlet?js=foo

would result in:

foo(84.1);

Whenever we looked in the browser, we were just looking at:

http://monitor.302br.net/MonitorScoreServlet?js

which resulted in:

(84.1);

I assumed jQuery was doing some magic with that to turn it into usable data, but now I think that jQuery was creating something like:

function jsonp1298047240882(data) {
    // do something with data
}

So when we changed our back-end code not to create the callback function call, the whole thing stopped working. (It’s still weird that the beforeSend handler never gets called, though.)