Flaw in calendar script

[Philip M]

I have adapted the following script (which resides in a .js file) which originally showed calendars for LAST MONTH..THIS MONTH..NEXT MONTH to show instead THIS MONTH..NEXT MONTH..MONTH AFTER THAT.

It works fine at present but I have not been able to make it work properly at the end of a year (current month = November or December).

Could some kind person suggest how to modify it to overcome this flaw. NEXT MONTH is fine, but the trouble comes with MONTH AFTER THAT when that month is in next year.


var flg = 0;
var fs = 1;
var bg = "#C0FFFF";
M = new Array("January","February",
"March","April","May","June",
"July","August","September",
"October","November","December");
D = new Array("Sun","Mon","Tue","Wed","Thu","Fri","Sat");

function getBgn() {
pdy = new Date(); // today
pmo = pdy.getMonth(); // present month
pyr = pdy.getYear(); // present year
if (pyr < 2000)
pyr = pyr + 1900;
yr = yr1 = (pmo==0?pyr-1yr); // last month's year
mo = (pmo==0?11mo-1); // last month
bgn = new Date(M[mo]+" 1,"+yr1); // assign to date
document.write('<TABLE BORDER=0><TR><TD VALIGN=TOP>');

document.write('</TD><TD VALIGN=TOP>');
yr = pyr; // present year
mo = pmo; // present month
bgn = new Date(M[mo]+" 1,"+yr); // assign to date
Calendar(); // Send this month to screen

document.write('</TD><TD VALIGN=TOP>');
yr = (pmo==11?pyr+1yr); // next month's year
mo = (pmo==11?0mo+1); // next month
bgn = new Date(M[mo]+" 1,"+yr); // assign to date
Calendar(); // Send next month to screen

document.write('</TD><TD VALIGN=TOP>');
yr = (pmo==11?pyr+2yr); // next month's year
mo = (pmo==11?0mo+2); // next month
bgn = new Date(M[mo]+" 1,"+yr); // assign to date
Calendar(); // Send third month to screen

document.write('</TD></TR></TABLE>'); // Finish up
}
function Calendar(){
dy = bgn.getDay();
yr = eval(yr);
d = "312831303130313130313031";
if (yr / 4 == Math.floor(yr / 4)) {
d = d.substring(0, 2) + "29" + d.substring(4, d.length);
}
pos = (mo * 2);
ld = eval(d.substring(pos, pos + 2));
document.write("<TABLE BORDER=1"
+ " BGCOLOR='" + bg
+ "'><TR><TD ALIGN=CENTER COLSPAN=7>"
+ "<FONT SIZE=" + fs + ">" + M[mo] + " " + yr
+ "</FONT></TD></TR><TR><TR>");
for (var i = 0;i < 7;i ++) {
document.write("<TD ALIGN=CENTER>"
+"<FONT SIZE=1>" + D[i] + "</FONT></TD>");
}
document.write("</TR><TR>");
ctr = 0;
for (var i = 0;i < 7; i++){
if (i < dy) {
document.write("<TD ALIGN=CENTER>"
+"<FONT SIZE=" + fs + "> </FONT>"
+"</TD>");
}
else {
ctr++;
document.write("<TD ALIGN=CENTER>"
+ "<FONT SIZE=" + fs + ">" + ctr + "</FONT>"
+ "</TD>");
}
}
document.write("</TR><TR>");
while (ctr < ld) {
for (var i = 0;i < 7; i++){
ctr++;
if (ctr > ld){
document.write("<TD ALIGN=CENTER>"
+ " </TD>");
}
else {
document.write("<TD ALIGN=CENTER>"
+ "<FONT SIZE=" + fs + ">" + ctr + "</FONT>"
+ "</TD>");
}
}
document.write("</TR><TR>");
}
document.write("</TR></TABLE>");}

=============================================


<SCRIPT language=\"JavaScript\">getBgn();</SCRIPT>


Any assistance much appreciated!

[Skyzyx]

I came across a similar problem when I was programming my own calendar script.

The problem lies with this: Mathematically, the number after 12 (December) is 13. You need to do a check for the current year, and as the month goes over the 12 mark into 13, you need to add a year, then subtract 12 months. You'd use the reverse when you're going backwards from January to December.

Getting those months/years to rollover is a bit of a pain.

[Philip M]

Thanks Skyzyx!

I have fixed it now.

If anyone is interested, the following changes make the third month appear OK after ayear end roll-over:-

document.write('</TD><TD VALIGN=TOP>');
yr = (pmo==10?pyr+1yr); // next month's year
if (pmo==11) {yr=pyr+1}
mo = (pmo==10?0mo+2); // next month is January
mo = (pmo==11?1mo+2); // next month is February
if (mo>11) {mo=mo-12}
bgn = new Date(M[mo]+" 1,"+yr); // assign to date
Calendar(); // Send third month to screen