jsonp的简单实现

jsonp: function(url, data, callback){
            if( wfQuery.isFunction(data) ){
                callback = data;
                data = {};
            }
            var cbk_name = "wfQuery_" + +new Date;
            data.__t = +new Date;
            data.callback = cbk_name;
            var _sc = doc.createElement(‘script‘);
                _sc.src = url + ‘?‘ + wfQuery.param( data );
            var sc = wfQuery(_sc);
            wfQuery(‘body‘).append( sc );

            window[cbk_name] = callback || function(){};
            sc.on(‘load‘,function(){
                delete window[cbk_name];
                sc.remove();
            });
        }