code: function getPath(url, root) {
          var ret;
  
          root = root || config.path;
          root = root.substr(0, root.lastIndexOf('/'));
          id = url;//模块id
  
          if(regAlias.test(url) && alias[url]){
              ret = alias[url];
  
          }else if(regProtocol.test(url)) { //如果用户路径包含协议
              ret = url;
          } else {
              var tmp = url.charAt(0),
                  _2 = url.slice(0, 2);
  
              if(tmp !== '.' && tmp !== '/') { //相对于根路径
                  ret = root + '/' + url;
              } else if(_2 === './') { //相对于兄弟路径
                  id = url.substr(2);
                  ret = root + '/' + id;
              } else if(_2 === '..') { //相对于父路径
                  // var arr = root.replace(/\/$/, '').split('/');
                  var arr = root.split('/');
                  regRelative.lastIndex = 0;
                  tmp = url.replace(regRelative, function() {
                      arr.pop();
                      return '';
                  });
                  id = tmp;
                  ret = arr.join('/') + '/' + tmp;
              }
          }
  
          var ext = 'js'; //默认是js文件
          tmp = ret.replace(/[?#].*/, '');
          if(regEXT.test(tmp)) {
              ext = RegExp.$1;
          }
          if(ext !== 'css' && tmp === ret && !regISJS.test(ret)) { //如果没有后缀名会补上.js
              ret += '.js';
          }
          return [ret, ext, id];
      }
docs: 后缀2~4 
  获取真实url
  来自massframework
  @param  {[type]} url [description]
  @return {[type]}     [description]