Question

I’m doing a GET with ajax using dataType jsonp to bring in a small xml file from a server on another domain which I don’t own and can’t change. Any dataType other than jsonp fails with a “Origin localhost is not allowed by Access-Control-Allow-Origin. Fine.

The problem is that the server returns the same xml response when I say it’s jsonp and jQuery doesn’t seem to like this. dataFilter doesn’t seem to help as the instant I refer to the returned data I get an “Uncaught SyntaxError: Unexpected token <” error. Maybe there’s some other way to use the dataFilter setting?

My code is reproduced below:

$(document).ready(function(){  
  $.ajax({
    type: "GET",  
    url: "https://b2b.firstenergycorp.com/invoke/ ... very long url... ",  
    dataType: "jsonp",
    dataFilter: function(data, type){
      if(type == "xml") alert("returned xml!");
      var newdata = data.replace(/</g, '{');   // Firebug complains about this
      newdata = newdata.replace(/>/g, '}');
      return newdata;
    },
    jsonp: "callback",
    jsonpCallback: "jsonpcallback"
  });  
  function jsonpcallback(returndata) {
    alert( "data returned: " + returndata );
  };
});      

Answer 1

the answer came in another stackoverflow question:
Jquery success function not firing using JSONP

“… In hindsight, the solution probably should have been more obvious than it was, but you need to have the web-response write directly to the response stream. Simply returning a string of JSON doesn’t do it, you need to someone construct it and stream it back.