The date object is what you would use. His client will provide his client-side time/date. You can place that info in a hidden field of the form that he submits.
Notice that there's no guarantee that you will obtain a correct time and date. You might have 1980 for the year, or 2038, depending on how the client's computer is set up.
You may just want to get their time zone offset, so that you can apply that to the server time and date.