How to read the start date value to validate enddate value before saving a record

Hello Community,

I wanted to validate Start date and enddate. For start date I will use current date to validate. But to validate EndDate I wanted the value of Startdate field. 

I want to know how to read the startdate attribute value in the end date validator. 

I am able to get the value of the attribute in handler, But i could not get value in the validators

"usr.usrenddatevalidator":{

                "validator": function(config){

                    return function(control){

                        var date1 = new Date();

                        var date2 = new Date(control.value);

                        var date3 = startdateAttributeValue;

                        return (date2 < date1 || date3 >= date2) ?  {"usr.usrenddatevalidator": { message: config.message }} : null;

                    };

                },

                "params":[

                    {"name":"message"}

                   ],

                "async":false

            },

Thanks in Advance 

Gargeyi.G