使用jquery和ajax获取RSS feed

Question

I found this site that allows to convert RSS feeds into json. It also provides a way to specify a callback, so i think users are able to make jsonp calls to this web service. However, i tried different ways to do that but none worked. Here is my code:

$(document).ready(function () {
    $.ajax({
        type: "GET",
        url: 'http://www.blastcasta.com/feed-to-json.aspx',
        dataType: "jsonp",
        jsonpCallback: "loadRSS",
        data: {
            feedUrl: 'http://xml.corriereobjects.it/rss/homepage.xml',
            param: "callback"
        },
        success: function (data) {
           var list = "";
           for (var propertyName in data) {
                list+=data[propertyName];
            }
            console.log(list);
        },
        error: function(xhr, ajaxOptions, thrownError){
            alert(ajaxOptions)
        }
    });
});

Whatever i try, the success handler doesn't get executed. I get error handler instead. I tried with jsonpCallbak: "callback", jsonpCallback: "?", param: "callback" and other values too but without success. I have to use ONLY javascript without the support any server side scripting language (no aps, no php, etc.) Did someone get this service working in his site? Any suggestion would be really appreciated!

Answer 1

I find jQuery JSON API not suitable for this kind of JSON response that provides BlastCasta service. It assigns JSON to a custom variable, specified in URL, and doesn't uses callback functionality JSONP operates with. For example this URL: http://www.blastcasta.com/feed-to-json.aspx?feedUrl=http%3A//xml.corriereobjects.it/rss/homepage.xml&param=rssFeed will return following response:

rssFeed = { "rss": { "channel": /*...*/}}

So, script injection technic may be used:

/* URL of the BlastCasta service and his parameters:
  feedUrl :== escaped URL of interest (RSS Feed service)
  param   :== javascript variable name which will receive parsed JSON object */
var url = "http://www.blastcasta.com/feed-to-json.aspx"
  +"?feedUrl=http%3A//xml.corriereobjects.it/rss/homepage.xml"
  +"&param=rssFeed";

/* since the service declares variable without var keyword,
   hence in global scope, lets make variable usage via window object;
   although you can write param=var%20rssFeed" in the URL :) */
window.rssFeed = null;

$.getScript(url, function() {
  /* script is loaded, evaluated and variable is ready to use */
  console.dir(window.rssFeed);

  /* some feeds are huge, so free the memory */
  window.rssFeed = null;
});

Answer 2

Update:

here's an example that works for your code:

$.getJSON("http://www.blastcasta.com/feed-to-json.aspx?feedUrl=http://xml.corriereobjects.it/rss/homepage.xml&param=?", function(data) {
    console.dir(data);
});

problem is, that I get some javascript errors with returning json:

see this jsfiddle