jquery-ui – JQuery UI自动完成语法

它利用了远程源的JQuery UI Autocomplete.我尽可能地评论了代码,然后是一个更精确的问题.

$( "#city" ).autocomplete({
        source: function( request,response )  {
//request is an objet which contains the user input so far
// response is a callback expecting an argument with the values to autocomplete with
            $.ajax({
                url: "http://ws.geonames.org/searchJSON",//where is script located 
                dataType: "jsonp",//type of data we send the script
                data: { //what data do we send the script 
                    featureClass: "P",style: "full",maxRows: 12,name_startsWith: request.term
                },success: function( data ) { //CONFUSED!
                    response( 
                        $.map( 
                        data.geonames,function( item ) { 
                                            return {
                                                    label: item.name+(item.adminName1 ? ","+item.adminName1:"")+","+item.countryName,value: item.name
                                            }
                                        }
                        )
                    );
                  }
            });
        }
    });

如您所见,我不理解成功函数和响应回调的使用.

我知道success function literal是一个AJAX选项,在AJAX查询返回时调用.在这种情况下,它似乎封装了对响应回调的调用？哪个定义在哪里？我认为根据回调的定义,它应该自己调用？

谢谢！