A Dynamic Calendar Table
/*
JavaScript Bible, Fourth Edition
by Danny Goodman
John Wiley & Sons CopyRight 2001
*/
<HTML>
<HEAD>
<TITLE>JavaScripted Dynamic Table</TITLE>
<SCRIPT LANGUAGE="JavaScript">
<!-- start
// function becomes a method for each month object
function getFirstDay(theYear, theMonth){
var firstDate = new Date(theYear,theMonth,1)
return firstDate.getDay()
}
// number of days in the month
function getMonthLen(theYear, theMonth) {
var oneDay = 1000 * 60 * 60 * 24
var thisMonth = new Date(theYear, theMonth, 1)
var nextMonth = new Date(theYear, theMonth + 1, 1)
var len = Math.ceil((nextMonth.getTime() -
thisMonth.getTime())/oneDay)
return len
}
// correct for Y2K anomalies
function getY2KYear(today) {
var yr = today.getYear()
return ((yr < 1900) ? yr+1900 : yr)
}
// create basic array
theMonths = new MakeArray(12)
// load array with English month names
function MakeArray(n) {
this[0] = "January"
this[1] = "February"
this[2] = "March"
this[3] = "April"
this[4] = "May"
this[5] = "June"
this[6] = "July"
this[7] = "August"
this[8] = "September"
this[9] = "October"
this[10] = "November"
this[11] = "December"
this.length = n
return this
}
// deferred function to fill fields of table
function populateFields(form) {
// initialize variables for later from user selections
var theMonth = form.chooseMonth.selectedIndex
var theYear = form.chooseYear.options[form.chooseYear.selectedIndex].text
// initialize date-dependent variables
// which is the first day of this month?
var firstDay = getFirstDay(theYear, theMonth)
// total number of <TD>...</TD> tags needed in for loop below
var howMany = getMonthLen(theYear, theMonth)
// set month and year in top field
form.oneMonth.value = theMonths[theMonth] + " " + theYear
// fill fields of table
for (var i = 0; i < 42; i++) {
if (i < firstDay || i >= (howMany + firstDay)) {
// before and after actual dates, empty fields
// address fields by name and [index] number
form.oneDay[i].value = ""
} else {
// enter date values
form.oneDay[i].value = i - firstDay + 1
}
}
}
// end -->
</SCRIPT>
</HEAD>
<BODY>
<H1>Month at a Glance (Dynamic)</H1>
<HR>
<SCRIPT LANGUAGE="JavaScript">
<!-- start
// initialize variable with HTML for each day's field
// all will have same name, so we can access via index value
// empty event handler prevents
// reverse-loading bug in some platforms
var oneField = "<INPUT TYPE='text' NAME='oneDay' SIZE=2 onFocus=''>"
// start assembling HTML for raw table
var content = "<FORM><CENTER><TABLE BORDER>"
// field for month and year display at top of calendar
content += "<TR><TH COLSPAN=7><INPUT TYPE='text' NAME='oneMonth'></TH></TR>"
// days of the week at head of each column
content += "<TR><TH>Sun</TH><TH>Mon</TH><TH>Tue</TH><TH>Wed</TH>"
content += "<TH>Thu</TH><TH>Fri</TH><TH>Sat</TH></TR>"
content += "<TR>"
// layout 6 rows of fields for worst-case month
for (var i = 1; i < 43; i++) {
content += "<TD ALIGN='middle'>" + oneField + "</TD>"
if (i % 7 == 0) {
content += "</TR><TR>"
}
}
content += "</TABLE>"
// blast empty table to the document
document.write(content)
// end -->
</SCRIPT>
<SELECT NAME="chooseMonth">
<OPTION SELECTED>January<OPTION>February
<OPTION>March<OPTION>April<OPTION>May
<OPTION>June<OPTION>July<OPTION>August
<OPTION>September<OPTION>October<OPTION>November<OPTION>December
</SELECT>
<SELECT NAME="chooseYear">
<OPTION SELECTED>2000<OPTION>2001
<OPTION>2002<OPTION>2003
<OPTION>2004<OPTION>2005
<OPTION>2006<OPTION>2007
</SELECT>
<INPUT TYPE="button" NAME="updater" VALUE="Update Calendar" onClick="populateFields(this.form)">
</FORM>
</BODY>
</HTML>
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