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Leap Yr regular expression

can someone give the regular expr. to validate leap yr like


Feb 17 '06
22 4464
On Sun, 19 Feb 2006 01:25:04 +0200, Dr John Stockton
<jr*@merlyn.dem on.co.uk> wrote:
It's curious, but I found this working with ALL known (for me) browsers:

function isLeapYear(year ) {

return ((new Date(year, 1, 29, 0, 0).getMonth() == 2) ? 0 : 1);

A function of that nature should return a Boolean :

return new Date(year, 1, 29, 0, 0).getMonth() != 2

Originally it was a function returning the number of days in February,

return ((new Date(year, 1, 29, 0, 0).getMonth() == 2) ? 28 : 29);

I need nothing more than that in my systems. And I just corrected this
function to the needs
of this topic. Of course, it must have been improved.

Feb 20 '06 #21
Vladas Saulis wrote:
[...] Michael Winter [...] wrote:
On 18/02/2006 18:08, Vladas Saulis wrote:
When you create a date = YYYY.02.29 for a non-leap year, you get back
a YYYY.03.01. And the getMonth() for the "March" is equal to 2 (for
february = 1).
That's why I called it kinda an exploit (unexpected (for me)
behaviour). However, it /is/ expected behaviour. The Date object is well-known for
handling out-of-range values by adjusting adjacent fields. It does this
by design.

Following this logic, then the date = YYYY.MM.00 should return the last
day of the previous month.

Am I right?
You are.
(I have no time to test :).


javascript:wind ow.alert(new Date(2000, 1, 0));

into your location bar and hit the Return key is too much for you?
Feb 20 '06 #22
JRS: In article <op.s47pc7qy8lq gld@eightpee>, dated Sun, 19 Feb 2006
10:47:21 remote, seen in news:comp.lang. javascript, Vladas Saulis
<vl****@prodata .lt> posted :

Following this logic, then the date = YYYY.MM.00 should return the last
day of the previous month.
Am I right? (I have no time to test :).

Use the newsgroup FAQ, and you will learn such things; see below.

With at least one localisation new Date("2005.01.0 0") gives NaN, as
does new Date("2005-01-00") -- but new Date("2005/01/00")
gives me Fri Dec 31 00:00:00 UTC 2004 and should set the local
equivalent of that anywhere.

One can get St Andrew's Day as new Date((year+1)+"/0/0") .

Also read <URL:http://www.merlyn.demo n.co.uk/js-quick.htm>.

© John Stockton, Surrey, UK. ?@merlyn.demon. co.uk Turnpike v4.00 IE 4 ©
<URL:http://www.jibbering.c om/faq/> JL/RC: FAQ of news:comp.lang. javascript
<URL:http://www.merlyn.demo n.co.uk/js-index.htm> jscr maths, dates, sources.
<URL:http://www.merlyn.demo n.co.uk/> TP/BP/Delphi/jscr/&c, FAQ items, links.
Feb 20 '06 #23

This thread has been closed and replies have been disabled. Please start a new discussion.

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