Date calculator, add or subtract days to or from a given date

**Lee** · Jul 23 '05, 06:09 PM

Re: Date calculator, add or subtract days to or from a given date

dlx_son@yahoo.c om said:[color=blue]
>
>Here is the code so far[/color]
[color=blue]
>I would like to click on the submit button and then some kind of alert
>window would pop up. Or just write it on the page.[/color]

What class is this for?

**Samir** · Jul 23 '05, 06:09 PM

Re: Date calculator, add or subtract days to or from a given date

It's not for a class,

Here's the Original Code, I am trying to change to use in a more useful
form for me, and ebay too.

<form>
<input type="text" name="date1" size="20"><br>
date (yyyy/mm/dd)<br><br>
<input type="text" name="date2" size="20" readonly><br>
90 days from date<br><br>
<input type="button" value="Calculat e"
onclick="plus90 (this);">
</form>

<script type="text/javascript">

document.forms( 0).date1.value = dateToString(ne w Date())

function dateToString(d) {
return [d.getYear(),d.g etMonth()+1,d.g etDate()].join('/')

}

function plus90(x){
d = new Date(x.form.dat e1.value)
d = new Date(d.getYear( ),d.getMonth(), d.getDate()+90)
x.form.date2.va lue = dateToString(d)

}

</script>

**RobG** · Jul 23 '05, 06:10 PM

Re: Date calculator, add or subtract days to or from a given date

Samir wrote:
[...][color=blue]
> <form>[/color]

<form action="">

[...][color=blue]
>
> document.forms( 0).date1.value = dateToString(ne w Date())[/color]

document.forms[0].date1.value = dateToString(ne w Date())
--------------^-^

<URL:http://www.jibbering.c om/faq/faq_notes/square_brackets .html>
[color=blue]
>
> function dateToString(d) {
> return [d.getYear(),d.g etMonth()+1,d.g etDate()].join('/')[/color]

getYear() will return the year from 1900 (unless you are using
IE, which does not properly implement getYear). You should
either use getFullYear() or for wider support, create your own
full year function:

return [
myFullYear(d.ge tYear()),
d.getMonth()+1,
d.getDate()
].join('/')

function myFullYear(y){
return (y<1900)?y+1900 :y;
}
[color=blue]
> }
>
> function plus90(x){
> d = new Date(x.form.dat e1.value)
> d = new Date(d.getYear( ),d.getMonth(), d.getDate()+90)[/color]

Why generate an entirely new date?

function plus90(x){
d = new Date(x.form.dat e1.value)
d.setDate(d.get Date()+90);

[...]

given the above, subtracting days should be simple easy. As for
time, you should convert the change in hours, minutes and
seconds to milliseconds, then use:

var changeInMillise conds = 1000 * (
hoursEntered *60*60
+ minutesEntered *60
+ secondsEntered * 1);

d.setTime(d.get Time() + changeInMillise conds);

secondsEntered needs to be converted from a string to number,
hence *1, which is a nice way of doing it in sync with the other
variables.

Using milliseconds this way to adjust the time is not perfect,
but pretty darn close for short time intervals. I've also
tossed in a function to add leading zeros to single digit
numbers in the date string. Full code below.

--
Rob

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title>Time play</title>
<meta http-equiv="Content-Type"
content="text/html; charset=ISO-8859-1">

<script type="text/javascript">
function dateToString(d) {
var dateString = myFullYear(d.ge tYear())
+ '/' + addZ(d.getMonth ()+1)
+ '/' + addZ(d.getDate( ))
+ ' ' + addZ(d.getHours ())
+ ':' + addZ(d.getMinut es())
+ ':' + addZ(d.getSecon ds())
return dateString;
}

function myFullYear(y){
return ( y < 1900 )? y + 1900 : y;
}

function plus90(x){
d = new Date(x.form.dat e1.value)
d.setDate(d.get Date()+90);
x.form.date2.va lue = dateToString(d) ;
document.getEle mentById('msgBo x').innerHTML = dateToString(d) ;
}

function addTime(x){
var tBit = x.form.timeChan ge.value.split( ':');
var changeInMillise conds = 1000 * (
tBit[0] *60*60
+ tBit[1] *60
+ tBit[2] * 1);

d.setTime(d.get Time() + changeInMillise conds);
x.form.date2.va lue = dateToString(d) ;
document.getEle mentById('msgBo x').innerHTML = dateToString(d) ;
}

function addZ(z) {
return (z<10)? '0' + z : z;
}

</script>

</head>

<body>
<form action="">
<input type="text" name="date1" size="20"><br>
date (yyyy/mm/dd)<br><br>
<input type="text" name="date2" size="20" readonly><br>
90 days from date<br>
<input type="text" name="timeChang e" size="20"
value="03:12:37 ">
<br>
<input type="button" value="Add 90 days"
onclick="plus90 (this);">
<br>
<input type="button" value="Add time"
onclick="addTim e(this);">
<br>
<input type="reset">
</form>
<span id="msgBox"></span>

<script type="text/javascript">
document.forms[0].date1.value = dateToString(ne w Date())
</script>

</body>
</html>

**RobG** · Jul 23 '05, 06:10 PM

Re: Date calculator, add or subtract days to or from a given date

RobG wrote:
[...][color=blue]
> function myFullYear(y){
> return (y<1900)?y+1900 :y;
> }[/color]

Ooops, the above works fine in Mozilla-based browsers for all
relevant (post 1 AD) years, however it will fail in IE for dates
below 1900. A better (but not perfect) myFullYear is:

function myFullYear(y){
return ( y < 999 )? y + 1900 : y;
}

This still works fine in the 'Zillas, but will give erroneous
results in IE for years before 999. Presumably any usage related
to eBay does not require coverage for this time frame. :-x

For further information, read here:

<URL:http://www.merlyn.demo n.co.uk/js-date0.htm#gFY>

--
Rob

**Dr John Stockton** · Jul 23 '05, 06:10 PM

Re: Date calculator, add or subtract days to or from a given date

JRS: In article <1109279414.067 200.49780@g14g2 000cwa.googlegr oups.com>,
dated Thu, 24 Feb 2005 13:10:14, seen in news:comp.lang. javascript,
Samir <dlx_son@yahoo. com> posted :
[color=blue]
>Here's the Original Code, I am trying to change to use in a more useful
>form for me, and ebay too.
>
><form>
> <input type="text" name="date1" size="20"><br>
> date (yyyy/mm/dd)<br><br>
> <input type="text" name="date2" size="20" readonly><br>
> 90 days from date<br><br>
> <input type="button" value="Calculat e"
> onclick="plus90 (this);">
></form>
>
><script type="text/javascript">
>
>document.forms (0).date1.value = dateToString(ne w Date())
>
>function dateToString(d) {
> return [d.getYear(),d.g etMonth()+1,d.g etDate()].join('/')
>
>}
>
>function plus90(x){
> d = new Date(x.form.dat e1.value)
> d = new Date(d.getYear( ),d.getMonth(), d.getDate()+90)
> x.form.date2.va lue = dateToString(d)
>
>}
>
></script>[/color]

You should validate the input date. In a Murrican-infested world, you
must expect to get dates written as 2/25/05, whatever you ask for.
Validation can return a Date Object. But perhaps you have not yet
bothered to read the newsgroup FAQ with care? See sig.

Function dateToString should give YYYY-MM-DD, since that is the
standard. So you should use a leading zero function. I doubt whether
it is worth creating an array and then joining it; I would use
with (d)
return getFullYear()+'-'+LZ(getMonth() +1)+'-'+LZ(getDate())

Input should match that, so use .replace(/-/g, "/") or similar; but,
in combining getting an Object with validation, that becomes irrelevant.

It is strange that you have learned that new Date() accepts
extended-range fields but are not using setDate() in that manner -
d.setDate(d.get Date()+90)

Better, IMHO, to pass this.form into plus90()

Better to use a named form rather than relying on it being forms(0)
- should that be forms[0] anyway?

--
© 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.

**Dr John Stockton** · Jul 23 '05, 06:11 PM

Re: Date calculator, add or subtract days to or from a given date

JRS: In article <VIwTd.30$Zn.33 82@news.optus.n et.au>, dated Fri, 25 Feb
2005 03:12:53, seen in news:comp.lang. javascript, RobG
<rgqld@iinet.ne t.auau> posted :[color=blue]
>
> function plus90(x){
> d = new Date(x.form.dat e1.value)
> d.setDate(d.get Date()+90);[/color]

That gives the same local time (if it exists; 1 chance in 8766 currently
that it does not) 90 days on.

[color=blue]
> given the above, subtracting days should be simple easy. As for
> time, you should convert the change in hours, minutes and
> seconds to milliseconds, then use:
>
> var changeInMillise conds = 1000 * (
> hoursEntered *60*60
> + minutesEntered *60
> + secondsEntered * 1);
>
> d.setTime(d.get Time() + changeInMillise conds);[/color]

That moves ahead by a certain absolute interval.

If the hours entered are 90*24 = 2160, then there is about a 50% chance,
in many locations, that it will not give the same result as plus90.

The OP should be aware of this.

--
© 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.

**Dr John Stockton** · Jul 23 '05, 06:11 PM

Re: Date calculator, add or subtract days to or from a given date

JRS: In article <o_wTd.32$Zn.34 36@news.optus.n et.au>, dated Fri, 25 Feb
2005 03:31:32, seen in news:comp.lang. javascript, RobG
<rgqld@iinet.ne t.auau> posted :[color=blue]
> A better (but not perfect) myFullYear is:
>
> function myFullYear(y){
> return ( y < 999 )? y + 1900 : y;
> }[/color]

For current dates, return 2000 + y%100 works with all three
behaviours of getYear() that I've heard of.

--
© 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.

**Lubna tt** · Jul 23 '05, 09:00 PM

Re: Date calculator, add or subtract days to or from a given date

Lubnatariq@hotm ail.com

*** Sent via Developersdex http://www.developersdex.com ***

Date calculator, add or subtract days to or from a given date

Date calculator, add or subtract days to or from a given date

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