Может кто нибудь прокомментировать подробнее. Это скрипт календаря. Мне нужно объяснить преподу

function montharr(m0, m1, m2, m3, m4, m5, m6, m7, m8, m9, m10, m11) {
this[0] = m0;
this[1] = m1;
this[2] = m2;
this[3] = m3;
this[4] = m4;
this[5] = m5;
this[6] = m6;
this[7] = m7;
this[8] = m8;
this[9] = m9;
this[10] = m10;
this[11] = m11;
}
function calendar() {
var monthNames = " ЯнвФевMaрАпрMaйИюнИюлАвгСенОктНояДек";
var today = new Date();
var thisDay;
var monthDays = new montharr(31, 28, 31, 30, 31, 30, 31, 31, 30,31, 30, 31);
year = today.getYear();
if (year < 2000)
year = year + 1900;
thisDay = today.getDate();
if (((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0))
monthDays[1] = 29;
nDays = monthDays[today.getMonth()];
firstDay = today;
firstDay.setDate(1);
testMe = firstDay.getDate();
if (testMe == 2)
firstDay.setDate(0);
startDay = firstDay.getDay();
document.writeln("");
document.write("");
document.write("");
document.write(monthNames.substring(today.getMonth() * 3 + 3, (to-day.getMonth() + 1) * 3 + 3));
document.write(". ");
document.write(year);
document.write("Вск Пон Вт Ср Чт Пт Сб" );
document.write("");
column = 0;
for (i = 0; i < startDay; i++) {
document.write("");
column++;
}
for (i = 1; i <= nDays; i++) {
document.write("");
if (i == thisDay)
document.write("")
document.write(i);
if (i == thisDay)
document.write("")
column++;
if (column == 7) {
document.write("");
column = 0;
}
}
document.write("");
document.writeln("");
}