The approach of dynamically generating a callback script is more robust than pure JSONP. If your URL returns an error (e.g., 404), you immediately notice, inste

The approach of dynamically generating a callback script is more robust than pure JSONP. If your URL returns an error (e.g., 404), you immediately notice, instead of waiting for the time-out. These days, my usual approach looks something like this in flight: <script type="text/javascript"> var response = undefined; </script> <script type="text/javascript" src="..."> // response = { .... }; </script> <script type="text/javascript"> _callbacks[1234](response); // response == undefined means error response = undefined; // allow garbage collection </script> It's a bit more administration, but I really like not having to worry about dynamic callback names, delayed errors, or non-existent callback functions any more.