如何从Backbone的响应中访问responseText？

    var $ = require('jquery'),
        Handlebars = require('handlebars'),
        Backbone = require('backbone'),
        mainJs = require('./main');


var services = {



    authenticationservice: function(collections) {
         var jsonreturn;

         var api_token = mainJs.get_api_token();


        jsonreturn = collections.fetch({

        headers: {'Authorization': 'Bearer ' + api_token.access_token},
        success: function (collection, response, options) {

           var responsejson = JSON.parse(response.responseText);
           return responsejson;

        },

        error: function (collection,response,options){

            var errorjson = JSON.parse(response.responseText);
            //alert(errorjson.error_description);
             return errorjson;

        }
    });

        return jsonreturn; 



    }

};




module.exports = services;
    var $ = require('jquery'),
        Handleba