Design Patterns

184
CHAPTER 13 ■ THE FLYWEIGHT PATTERN
function isLeapYear(y) {
return (y > 0) && !(y % 4) && ((y % 100) || !(y % 400));
}
this.months = [];
// The number of days in each month.
this.numDays = [31, isLeapYear(this.year) ? 29 : 28, 31, 30, 31, 30, 31, 31, 30,
31, 30, 31];
for(var i = 0, len = 12; i < len; i++) {
this.months[i] = new CalendarMonth(i, this.numDays[i], this.element);
}
);
CalendarYear.prototype = {
display: function() {
for(var i = 0, len = this.months.length; i < len; i++) {
this.months[i].display(); // Pass the call down to the next level.
}
this.element.style.display = 'block';
}
};
/* CalendarMonth class, a composite. */
var CalendarMonth = function(monthNum, numDays, parent) { // implements CalendarItem
this.monthNum = monthNum;
this.element = document.createElement('div');
this.element.style.display = 'none';
parent.appendChild(this.element);
this.days = [];
for(var i = 0, len = numDays; i < len; i++) {
this.days[i] = new CalendarDay(i, this.element);
}
);
CalendarMonth.prototype = {
display: function() {
for(var i = 0, len = this.days.length; i < len; i++) {
this.days[i].display(); // Pass the call down to the next level.
}
this.element.style.display = 'block';
}
};
/* CalendarDay class, a leaf. */
var CalendarDay = function(date, parent) { // implements CalendarItem
this.date = date;
this.element = document.createElement('div');
this.element.style.display = 'none';