How i can chage the date formatt using java script?

Hi All,

I have a data field. In Object -> Valid patterns I changed the format as MM/DD/YYYY.

and i am writing the java script code on exit event of date field

var

reGoodDate =/^(?:(0[1-9]|1[012])[\/.](0[1-9]|[12][0-9]|3[01])[\/.](19|20)[0-9]{2})$/

;

if (reGoodDate.test(dt))

{

xfa.host.messageBox("Correct format")

}

else

{

xfa.host.messageBox("Incorrect Format");

}

but though i am giving the correct date formatt it is giving  as error message