//************************************************
// Author - Jonathan Grant
// Copyright - Jonathan Grant, 2005
// E-mail - Jonathan_Grant@jondaf.com
//************************************************
//************************************************
// This JavaScript code will enable three drop-down
// lists to be set up and displayed in a form to show
// dates and select them. It will check the selected
// year to see if it is a leap year and adjust the
// number of days in February to reflect this. It
// will also check the selected month and adjust
// the number of days available in it displayed.
//
// There are three SELECT statements required, for
// day, month and year. They can be in any order.
// The month and year SELECTs need an onChange
// event handler which calls the checkYear function
// to enable the corect number of days in the month
// to be available.
//
// The year SELECT can be one of three functions
// to display either a range of years from a given
// year to another given year, a range of years
// from a given year to a year calculated from the
// current year, or a range of years calculated
// from the current year.
//
// The reset function is necessary to reset the
// days in the month.
//************************************************
//************************************************
// Set up array of days in a month
//************************************************
monthDays = new Array(31,
28,
31,
30,
31,
30,
31,
31,
30,
31,
30,
31);
//************************************************
// Set up array of month names
//************************************************
monthName = new Array("January",
"February",
"March",
"April",
"May",
"June",
"July",
"August",
"September",
"October",
"November",
"December");
//************************************************
// Get todays date and year
//************************************************
todayDate = new Date();
todayDay = todayDate.getDate();
todayMonth = todayDate.getMonth();
todayYear = todayDate.getFullYear();
var defaultDaySelected;
//************************************************
// Function to check if a year is a leap year
//************************************************
function checkLeap(inYear) {
isLeap = 0;
if ((inYear % 4) == 0) {
isLeap = 1;
}
if ((inYear % 100) == 0) {
isLeap = 0;
if ((inYear % 400) == 0) {
isLeap = 1;
}
}
return isLeap;
}
//************************************************
// Functions to display a drop-down showing a list
// of years in different ways
//************************************************
//************************************************
// This function displays variable years from
// this year - start to this year + end
//************************************************
function displayYearVariable(firstYear, lastYear, presetDate, preDate) {
if (presetDate && (preDate != null)) {
startDate = new Date(preDate);
startDay = startDate.getDate();
startMonth = startDate.getMonth();
startYear = startDate.getFullYear();
}
else if (presetDate) {
startDay = todayDay;
startMonth = todayMonth;
startYear = todayYear;
}
for (count = (todayYear - firstYear); count <= (todayYear + lastYear); count++) {
document.write("");
}
}
//************************************************
// This function displays variable years from
// a static start year to this year + end
//************************************************
function displayYearStaticStart(firstYear, lastYear, presetDate, preDate) {
if (presetDate && (preDate != null)) {
startDate = new Date(preDate);
startDay = startDate.getDate();
startMonth = startDate.getMonth();
startYear = startDate.getFullYear();
}
else if (presetDate) {
startDay = todayDay;
startMonth = todayMonth;
startYear = todayYear;
}
for (count = firstYear; count <= (todayYear + lastYear); count++) {
document.write("");
}
}
//************************************************
// This function displays static years from
// a start year to end year
//************************************************
function displayYearStatic(firstYear, lastYear, presetDate, preDate) {
if (presetDate && (preDate != null)) {
startDate = new Date(preDate);
startDay = startDate.getDate();
startMonth = startDate.getMonth();
startYear = startDate.getFullYear();
}
else if (presetDate) {
startDay = todayDay;
startMonth = todayMonth;
startYear = todayYear;
}
for (count = firstYear; count <= lastYear; count++) {
document.write("");
}
}
//************************************************
// Function to display a drop-down showing a list
// of months
//************************************************
function displayMonth(presetDate, preDate) {
if (presetDate && (preDate != null)) {
startDate = new Date(preDate);
startDay = startDate.getDate();
startMonth = startDate.getMonth();
startYear = startDate.getFullYear();
}
else if (presetDate) {
startDay = todayDay;
startMonth = todayMonth;
startYear = todayYear;
}
for (count = 1; count <= 12; count++) {
document.write("");
}
}
//************************************************
// Function to display a drop-down showing a list
// of dates, 01 to 31
//************************************************
function displayDay(presetDate, preDate) {
if (presetDate && (preDate != null)) {
startDate = new Date(preDate);
startDay = startDate.getDate();
startMonth = startDate.getMonth();
startYear = startDate.getFullYear();
countDays = monthDays[startMonth];
leapYear = checkLeap(startYear);
defaultDaySelected = startDay;
}
else if (presetDate) {
startDay = todayDay;
startMonth = todayMonth;
startYear = todayYear;
countDays = monthDays[todayMonth];
leapYear = checkLeap(startYear);
defaultDaySelected = startDay;
}
else {
startMonth = 0;
countDays = 31;
leapYear = 0;
}
if (startMonth == 1) {
countDays = countDays + leapYear;
}
for (count = 1; count <= countDays; count++) {
document.write("");
}
}
//************************************************
// Function to check the range of dates displayed
// in the drop-down lists and to ensure that they
// are valid, adjusting the available dates as
// necessary
//
// This function requires three arguments:
// dayObj - the drop-down day object (this.form.dayObjName)
// monthObj - the drop-down month object (this.form.monthObjName)
// yearObj - the drop-down year object (this.form.yearObjName)
//************************************************
function checkYear(dayObj, monthObj, yearObj) {
yearValueInd = yearObj.selectedIndex;
yearValue = yearObj[yearValueInd].value;
monthValueInd = monthObj.selectedIndex;
monthValue = monthObj[monthValueInd].value;
dayValueInd = dayObj.selectedIndex;
dayValue = dayObj[dayValueInd].value;
dayValueSize = dayObj.length;
defaultDay = 0;
for (count = 1; count <= (dayValueSize - 1); count++) {
if (dayObj.options[count].defaultSelected) {
defaultDay = count;
}
}
//************************************************
// Check whether the selected year is a leap year
//************************************************
leapYear = checkLeap(yearValue);
//************************************************
// Get the number of days that the selected month
// has in it
//************************************************
totalDays = monthDays[parseInt(monthValue, 10) - 1];
//************************************************
// Check whether the selected month is February
// and if it is adjust the number of days in the
// month if it is a leap year
//************************************************
if (monthValue == 2) {
totalDays = totalDays + leapYear;
}
//************************************************
// Adjust the day drop-down to show the correct
// number of days available
//************************************************
dayObj.length = totalDays;
for (count = 1; count <= totalDays; count++) {
if (count < 10) {
countText = "0" + count;
}
else {
countText = count;
}
newOption = new Option(countText, count);
dayObj.options[count - 1] = newOption;
}
//************************************************
// Adjust the day currently displayed in the day
// drop down if it would now be outside of the
// number of actual days in the displayed month
//************************************************
if (totalDays <= dayValueInd) {
dayValueInd = (totalDays - 1);
}
dayObj.selectedIndex = dayValueInd;
if (totalDays <= defaultDay) {
dayObj.options[totalDays - 1].defaultSelected = true;
}
else {
dayObj.options[defaultDay].defaultSelected = true;
}
}
/*********************************************
* Reset function. This is necessary in case *
* a default start date has been used *
*********************************************/
function formReset(formObj, dayObj, monthObj, yearObj, presetDate, preDate) {
if (presetDate && (preDate != null)) {
startDate = new Date(preDate);
startDay = startDate.getDate();
startMonth = startDate.getMonth();
startYear = startDate.getFullYear();
countDays = monthDays[startMonth];
defaultDaySelected = startDay;
}
else if (presetDate) {
startDay = todayDay;
startMonth = todayMonth;
startYear = todayYear;
countDays = monthDays[startMonth];
defaultDaySelected = startDay;
}
else {
countDays = 31;
}
leapYear = checkLeap(startYear);
if (startMonth == 1) {
countDays = countDays + leapYear;
}
dayObj.length = countDays;
for (count = 1; count <= countDays; count++) {
if (count < 10) {
countText = "0" + count;
}
else {
countText = count;
}
newOption = new Option(countText, count);
dayObj.options[count - 1] = newOption;
}
if (presetDate) {
dayObj.options[defaultDaySelected - 1].defaultSelected = true;
}
return true;
}