Date-oddity

 
Hi
 
I have implemented a small web-solution, making use of the excellent
exslt-date-module (Javascript/MSXSL-version).
 
When using Date:Add I have experienced something odd, occuring only when the
date is the last date in the month(!).
 
My goal is to write a list of the month-names + year for 12 months, starting
with the month of the current date. For the date 2003-10-31 the list should
read october 2003, november 2003, december 2003, january 2004 an so forth
until september 2004. The code is appended at the end of this mail.
 
What I get (using the particular date 2003-10-31) is:
 
October  2003,
December  2003,
December  2003,
January  2004
March  2004
March  2004
May  2004
May  2004
July  2004
July  2004
August  2004
October  2004

Notice that several months is repeated and that some months is missing(!).
 
Using any other date than the last day in each month, the functionality
works fine. You can reproduce the oddity by setting the date on your
computer to 2003-10-31 and run the following debug code in Javascript (using
the Javascript/MSXSL-module):
 
add(_formatDate(new Date(), "xs:date"), 'P1M');
 
This will return 2003-12-01, which obviously is not the intended date.
 
What happens (in the EXSLT-module code), is that Javascript adds one day to
the temporary (and illegal) date 2003-11-31 because there is no 31. nov, and
thus ends up with 2003-12-01.
 
What I should do is use the first day in each month, because in my case the
day is not important, and this oddity will not occur.
 
This mail is therefore sent for information or discussion only.
 
Regards
Mvh
Tom Kise
 
A:
Julius Blomsgade 7, 3tv
2200 København
Danmark
 
M: [email protected]
T: 35828111
 
 <xsl:variable name="NoOfMonthInList" select="12"/>
 <xsl:variable name="Today" select="date:date()" />
 
 <xsl:template match="/">
  <xsl:call-template name="MonthLine">
   <xsl:with-param name="No" select="0"/>
  </xsl:call-template>
 </xsl:template>
 
 <xsl:template name="MonthLine">
  <xsl:param name="No"/>
  <xsl:if test="$NoOfMonthInList > $No">
   <xsl:variable name="aMonthNo"
select="date:monthInYear(date:parseDate(date:add($Today, concat(concat('P',
$No), 'M')), 'xs:dateTime', 'xs:date'))" />
   <xsl:variable name="aMonthName"
select="date:monthName(date:parseDate(date:add($Today, concat(concat('P',
$No), 'M')), 'xs:dateTime', 'xs:date'))" />
   <xsl:variable name="aYear"
select="date:year(date:parseDate(date:add($Today, concat(concat('P', $No),
'M')), 'xs:dateTime', 'xs:date'))" />
   <b>&#183;</b>&#160;
   <a href="/show.asp?id=2210&amp;MonthNo={$aMonthNo}&amp;Year={$aYear}">
 
    <xsl:value-of select="$aMonthName" />&#160;
    <xsl:value-of select="$aYear" />
   </a>
   <br/>
 
   <xsl:call-template name="MonthLine">
    <xsl:with-param name="No" select="($No)+1"/>
   </xsl:call-template>
  </xsl:if>
 </xsl:template>