calculating Num of days

**Maarten** · Jul 20 '05, 11:52 AM

Re: calculating Num of days

Check the source of http://www.westhavenbay.com/english/...kbaarheid.html

function aantalNachten(d ate1,date2) {
var verschil =

Date.UTC(y2k(da te1.getFullYear ()),date1.getMo nth(),date1.get Date(),0,0,0)
-
Date.UTC(y2k(da te2.getFullYear ()),date2.getMo nth(),date2.get Date(),0,0,0);

nachten = verschil/1000/60/60/24;

if (nachten < 1) nachten = 0;

document.RQ.NAC HTEN.value = nachten;

}

aantalNachten = number of nights
result is stored in nachten

**Michael Winter** · Jul 20 '05, 11:52 AM

Re: calculating Num of days

"riki" wrote on 14/11/2003:
[color=blue]
> hello,
> i need to calculate num of days between 2 dates...
> i get separate parts of dates from html form, then i need to "make"[/color]
begining[color=blue]
> and ending date and calculate difference between them...
> something like this, in sybase:
> DAYS(YMD(?YEAR? ,?MONTH?,?DAY?) , YMD(?YEAR1?,?MO NTH1?,?DAY1?))[/color]

If you create two Date objects, then subtract one from the other,
you'll get the number of milliseconds between them. For example:

var difference = new Date( 2003, 1, 6 ) - new Date( 2003, 1, 1 );
window.alert( difference / 1000 / 60 / 60 / 24 );

will display 5. If you reversed the order of the subtraction, you'd
get -5.

Mike

--
Michael Winter
M.Winter@[no-spam]blueyonder.co.u k (remove [no-spam] to reply)

**Michael Winter** · Jul 20 '05, 11:52 AM

Re: calculating Num of days

"Maarten" wrote on 14/11/2003:

<snip>
[color=blue]
>[/color]
Date.UTC(y2k(da te1.getFullYear ()),date1.getMo nth(),date1.get Date(),0,0
,0)

What is the function 'y2k' supposed to do, and what language is it
defined in? It's not native JavaScript or ECMAScript...

Mike

--
Michael Winter
M.Winter@[no-spam]blueyonder.co.u k (remove [no-spam] to reply)

**Dr John Stockton** · Jul 20 '05, 11:53 AM

Re: calculating Num of days

JRS: In article <pB9tb.4143$ZT2 .35402980@news-text.cableinet. net>, seen
in news:comp.lang. javascript, Michael Winter <M.Winter@[no-spam]> posted
at Fri, 14 Nov 2003 18:58:29 :-[color=blue]
>"riki" wrote on 14/11/2003:
>[color=green]
>> hello,
>> i need to calculate num of days between 2 dates...
>> i get separate parts of dates from html form, then i need to "make"[/color]
>begining[color=green]
>> and ending date and calculate difference between them...
>> something like this, in sybase:
>> DAYS(YMD(?YEAR? ,?MONTH?,?DAY?) , YMD(?YEAR1?,?MO NTH1?,?DAY1?))[/color]
>
>If you create two Date objects, then subtract one from the other,
>you'll get the number of milliseconds between them.[/color]

Correct.
[color=blue]
> For example:
>
>var difference = new Date( 2003, 1, 6 ) - new Date( 2003, 1, 1 );
>window.alert ( difference / 1000 / 60 / 60 / 24 );
>
>will display 5. If you reversed the order of the subtraction, you'd
>get -5.[/color]

Agreed.

But

var difference = new Date( 2003, 3, 23 ) - new Date( 2003, 1, 1 );
window.alert( difference / 1000 / 60 / 60 / 24 );

gives 80.958333333333 33 - the explanation can be found via below.

--
© John Stockton, Surrey, UK. ?@merlyn.demon. co.uk Turnpike v4.00 IE 4 ©
<URL:http://jibbering.com/faq/> Jim Ley's FAQ for news:comp.lang. javascript
<URL:http://www.merlyn.demo n.co.uk/js-index.htm> JS maths, dates, sources.
<URL:http://www.merlyn.demo n.co.uk/> TP/BP/Delphi/JS/&c., FAQ topics, links.

**Dr John Stockton** · Jul 20 '05, 11:53 AM

Re: calculating Num of days

JRS: In article <EU6tb.23011$jz 6.666734@phobos .telenet-ops.be>, seen in
news:comp.lang. javascript, Maarten <nobody@pandora .be> posted at Fri, 14
Nov 2003 15:54:12 :-
[color=blue]
> var verschil =
>
>Date.UTC(y2k(d ate1.getFullYea r()),date1.getM onth(),date1.ge tDate(),0,0,0)
> -
>Date.UTC(y2k(d ate2.getFullYea r()),date2.getM onth(),date2.ge tDate(),0,0,0);
>
> nachten = verschil/1000/60/60/24;[/color]

Whatever it is, the function y2k should not AFAICS be needed with
getFullYear(); but, if it is needed, I'd be pleased to see an example.

Date.UTC takes seven arguments. ECMA says that up to 5 can be omitted,
and default to 1 0 0 0 0 - therefore, it is strange to give 6 ending 0 0
0. But not wrong. Netscape says that exactly 4 can be omitted.

In MSIE 4, one can omit any number of arguments.

One can use
Math.round((new Date(2003, 3, 23) - new Date(2003, 1, 1))/864e5)

--
© John Stockton, Surrey, UK. ?@merlyn.demon. co.uk Turnpike v4.00 MIME. ©
Web <URL:http://www.merlyn.demo n.co.uk/> - w. FAQish topics, links, acronyms
PAS EXE etc : <URL:http://www.merlyn.demo n.co.uk/programs/> - see 00index.htm
Dates - miscdate.htm moredate.htm js-dates.htm pas-time.htm critdate.htm etc.

**riki** · Jul 20 '05, 11:55 AM

Re: calculating Num of days

thanks everyone

**riki** · Jul 20 '05, 11:55 AM

Re: calculating Num of days

hi,
i've tried everything you all proposed me to but can't get good solution to
my problem...
it works fine for 2 dates in the same month, but if starting date is in
different month than ending date, the calculation is incorrect...
for instance 2003.11.30 til 2003.12.02 --> number of days results 3, but it
should result 2 becouse november has 30 and not 31 days...
how should i deal with this problem???
thanks

**Dr John Stockton** · Jul 20 '05, 11:56 AM

Re: calculating Num of days

JRS: In article <bpal30$kd3$1@l s219.htnet.hr>, seen in
news:comp.lang. javascript, riki <riki_fox@hotma il.com> posted at Mon, 17
Nov 2003 15:13:53 :-[color=blue]
>i've tried everything you all proposed me to but can't get good solution to
>my problem...
>it works fine for 2 dates in the same month, but if starting date is in
>different month than ending date, the calculation is incorrect...
>for instance 2003.11.30 til 2003.12.02 --> number of days results 3, but it
>should result 2 becouse november has 30 and not 31 days...[/color]

Actually, there is only one day, 2003-12-01, between those dates; but
they do differ by two days.

See <URL:http://www.merlyn.demo n.co.uk/js-date2.htm##DDf> .

You will be aware of the probable need to replace . with / in your
dates.

If you had posted your code, we could have seen the error(s).

--
© John Stockton, Surrey, UK. ?@merlyn.demon. co.uk Turnpike v4.00 IE 4 ©
<URL:http://jibbering.com/faq/> Jim Ley's FAQ for news:comp.lang. javascript
<URL:http://www.merlyn.demo n.co.uk/js-index.htm> JS maths, dates, sources.
<URL:http://www.merlyn.demo n.co.uk/> TP/BP/Delphi/JS/&c., FAQ topics, links.

**Michael Winter** · Jul 20 '05, 11:56 AM

Re: calculating Num of days

riki wrote on 17 Nov 2003:
[color=blue]
> hi,
> i've tried everything you all proposed me to but can't get good
> solution to my problem...
> it works fine for 2 dates in the same month, but if starting
> date is in different month than ending date, the calculation is
> incorrect... for instance 2003.11.30 til 2003.12.02 --> number
> of days results 3, but it should result 2 becouse november has
> 30 and not 31 days... how should i deal with this problem???
> thanks
>
>[/color]

Were you making those comparisons like so (or an equivalent)?

var diff = new Date( 2003, 12, 2 ) - new Date( 2003, 11, 30 );
window.alert( diff / 86400000 ); // Displays 3

If so, that because the first date evaluates to 2-Jan-2004 and the
second to 30-Dec-2003.

As I very recently discovered, month ordinals are zero based (0 -
Jan, 1 - Feb, etc.) If you change the above to:

var diff = new Date( 2003, 11, 2 ) - new Date( 2003, 10, 30 );
window.alert( diff / 86400000 );

....you'll get 2, as you expect.

Mike

--
Michael Winter
M.Winter@[no-spam]blueyonder.co.u k (remove [no-spam] to reply)

**riki** · Jul 20 '05, 11:56 AM

Re: calculating Num of days

aha, so that's the catch...months are zero based.
thank you all very much :)

calculating Num of days

calculating Num of days

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