html - jquery custom validation rule -

in form used custom validation rule date format

$.validator.addmethod(         "usdate",         function(value, element) {             // date mm/dd/yyyy             return value.match(/^\d\d?\/\d\d?\/\d\d\d\d$/);          } ); 

in validator called

phone : {                 usdate: true         }, 

this working fine. need modify this rule called if phone field has filled something. if filed blank no need validate field.

and value.match(/^\d\d?\/\d\d?\/\d\d\d\d$/) working 25/80/1212 ...

but month 1 12 , date 1 31 ...

how change code. please me. thanks

$.validator.addmethod(         "usdate",         function(value, element) {             // date mm/dd/yyyy             return value.match(/^(0[0-9]|1[0-2])[\/](0[0-1]|1[0-9]|2[0-9]|3[0-1])[\/]\d{4}$/);          } ); 

in validator called as

phone : {                 required: true,                 usdate: true         },