javascript - JQuery JSONP randomly generated callback function -

i'm using jquery make jsonp requests , documentation quite confusing.

i have several questions:

• a jsonp call async, correct? async:false ignored?
• if jsonpcallback parameter specified, function executed when data retrieved. right after, success callback executed. jquery advices not specify jsonpcallback function(only caching?). role of function in relation success function?
• if jsonpcallback not specified random callback function created , attached window object. jquery1360574548776335413_1776656584447, role? how work? have relation success function?
• is error callback never called?

here's code:

(function($) {     var url = "https://www.googleapis.com/books/v1/volumes/zytcalfpjgyc";     $.ajax({         type: 'get',         url: url,         // jsonp async?         async: false,         jsonp: "callback",         jsonpcallback: 'jsoncallback',         contenttype: "application/json",         datatype: 'jsonp',         success: function(json) {             console.dir(json);         },         // error never called?         error: function(e) {             console.log(e.message);         }     }); })(jquery);  function jsoncallback(json) {     $(".test").html(json.volumeinfo.title); } 

a jsonp call async, correct? async:false ignored?

that correct

if jsonpcallback parameter specified, function executed when data retrieved. right after, success callback executed. jquery advices not specify jsonpcallback function(only caching?). role of function in relation success function?

the success function callback. jquery generates random function name usually. if, however, you're making several of same requests , instead allow browser cache calls, can specify function randomly generated 1 not created. inspect network requests , you'll see (as long server set support it) if specify name, should 304 - not modified (edit: on subsequent requests after first), while other calls return 200 ok

if jsonpcallback not specified random callback function created , attached window object. jquery1360574548776335413_1776656584447, role? how work? have relation success function? error callback never called?

that callback function should contain code put in success. error event fired if there error actual request, such invalid domain name, 401 server response, , etc.