Question

Consider:

var resturl = "http://example.com";
cj.getJSON(
    resturl + "&callback=?",        
    function(data)
    {
       console.log(data);
    }
);

My callback function is never called. Why?

Answer 1

Two things here:

First, your URL addition should be "?callback=?" since there’s no other querystring, or use the full $.ajax() call with a jsonp data type, so it adds the querystring as needed, like this:

$.ajax({
  url: resturl,
  dataType: 'jsonp',
  success: function(data){
    console.log( data );
  }
});

Second, the domain you’re going to has to support JSONP.