title: convert date to number of days then do stuff
body: <p>I want user to enter a date. Using a form, and in the background convert this to number of days. Then desuct a certain number of days, then convert that back to a date.</p>
  
  <p>Example:</p>
  
  <p>Enter the date you were born.</p>
  
  <p>-- convert to xx amount of days (dateindays)</p>
  
  <p>Then make newtotal=dateindays-280</p>
  
  <p>convert newtotal to a date.</p>
  
  <p>Can anyone point me in the right direction of doing this, or do they know some function for doing this?</p>
  
  <p>So lets say :user enters date 13th July 1980
  We use js to convert this to total number of days 11,453 days</p>
  
  <p>Then create new function : subtotal=11453-280</p>
  
  <p>And convert those number of days into a date, and echo back on screen.</p>