Webmaster Forum / HTML, CSS, Scripts / JavaScript / November 2004

[...]

 When you create a date object using year, month and day you may be
 trying to create a date outside the range that the browser can handle.
 Since you don't know what browser a user may be using, the easiest way
 is to test the date you create against the input you created it from
 (assuming you've validated that the input was OK in the first place,
 that is that the year is a number, month is between 1 and 12 inclusive
 and the day date between 1 and 31 inclusive).

 Consider the following function:

   function makeDate(y,m,d) {
     var theDate = new Date(y,m-1,d);
     return theDate;
   }

 Provided we call it with something like:

     alert('The date is ' + makeDate('2003','0','5'));

 we should get an alert telling us the date is 5 January, 2003.  In some
 browsers, (e.g. Safari) if we use:

     alert('The date is ' + makeDate('1803','0','5'));

 we'll get an error because it can't handle that dates before 1900 or
 after 2038 (most other browsers can).  So the best way to test is,
 after creating our date, to use:

     if(theDate.getMonth() != m || theDate.getDate() != d) {
       alert('Can't handle date ' + y +'-' + m + '-' + d);
       return false;
     } else {
       return theDate;
     }

 If you want to be really sure, add: || theDate.getFullYear() != y

 However, getFullYear() may not be implemented and rather than messing
 around with testing if it is or not, then seeing if the year is less
 than 1900 then adding 1900, just don't test the year.  The chance that
 the month and date will be OK but year incorrect is pretty slim (in
 this particular case).

 Having said that, if you are going to use getFullYear(), you must test
 that the browser supports it first and if not, use some alternative
 (say use getYear() and if it returns a value less than 1900, add 1900).

 For more fun, follow the link in Dr J's signature:

 <URL:http://www.merlyn.demon.co.uk/js-index.htm> jscr maths, dates,
sources.

JRS:  In article <41aa9a90@127.0.0.1>, dated Sun, 28 Nov 2004 21:46:32,
seen in news:comp.lang.javascript, KL <klbjornme@aohell.com> posted :

John Penn was born on the Julian Calendar; and so was everyone born in
the British Empire / Colonies before 1752-09-14 Gregorian.  The
particular date that he chose to appear exists in the Julian Calendar,
but not the Gregorian.  The javascript date object code treats the
Gregorian calendar as valid over the whole range.  For Julian calendar
methods, see <URL:http://www.merlyn.demon.co.uk/js-date8.htm#JCDM>.

I seek further interesting events of that date, other than the death of
Samuel Lathrop.