_proto_和prototype的区别

 if(typeof Object.getPrototypeOf!=="function"){
              if(typeof "test"._proto_==="object"){
                   Object.getPrototypeOf=function(object){
                        return object._proto_;
                    };
                }else{
                     Object.getPrototypeOf=function(object){
                        return object.constructor.prototype;
                      };
                  }
              }