Question

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.

Example:

Enter the date you were born.

— convert to xx amount of days (dateindays)

Then make newtotal=dateindays-280

convert newtotal to a date.

Can anyone point me in the right direction of doing this, or do they know some function for doing this?

So lets say :user enters date 13th July 1980
We use js to convert this to total number of days 11,453 days

Then create new function : subtotal=11453-280

And convert those number of days into a date, and echo back on screen.

Answer 1

var d1 = Date.parse("13 July 1980");
d1 = d1 - 24192000000; // 280 days in milliseconds

var newDate = new Date(d1);

console.log(newDate); // will return a date object that represents Oct 07 1979

Then use the following link to format it:
http://www.webdevelopersnotes.com/tips/html/10_ways_to_format_time_and_date_using_javascript.php3

Thanks to this SO question for the link:
Where can I find documentation on formatting a date in JavaScript?