^([1-9]0[1-9]1[0-2])/([1-9]0[1-9][1-2][0-9]3[01])/([1-9][0-9][0-9][0-9])$
It accepts following format
- mm/dd/yyyy
- m/d/yyyy
It accepts following value
- any value of month in between 01-12 or 1-12
- any value of day in between 01-31 or 1-31
- any value of year in between 1000-9999
