You need to use datepicker control. Please see the samples/02_form/01_init.html sample
The default date format is “%d.%m.%Y”
The format can be changed by dateFormat property in control configuration. If server date format is different from the displayed, you can use externalDateFormat for it (dateFormat - for displayed date)
If the user is allowed to type in an input, it will be impossible to apply formatting. For the Date of Birth you can choose different editor. For example it can be a combination of 3 selects: day, month, year.