Общие вопросы

Не могу понять почему при выполнении моего скрипта, при прокрутке дат, IE6 (WinXP) иногда виснет или падает с недопустимой ошибкой. При этом с Opera 7 все в порядке.

<style>

#div_datebox {

position: absolute;
visibility: hidden;
}

</style>

<script>

var month_label =
new Array('Январь',
'Февраль',
'Март',
'Апрель',
'Май',
'Июнь',
'Июль',
'Август',
'Сентябрь',
'Октябрь',
'Ноябрь',
'Декабрь');

var currentDate = new Date(),
workDate = new Date(), showDate = new Date();

workDate.setDate(workDate.getDate() + 2);

var datebox_isshow = false;

function compareDate(date1, date2) {

if ((date1.getYear() == date2.getYear()) &&
(date1.getMonth() == date2.getMonth()) &&
(date1.getDate() == date2.getDate())) return true;
else return false;
}

function get_normalDay(value_date) {

var ret = value_date.getDay() - 1;
if (ret == -1) ret = 6;
return ret;
}

function get_normalYear(value_date) {

var ret = value_date.getYear();
if (ret - 1900 < 100) ret += 1900;
return ret;
}

function clickDatebox() {

showDate = new Date(workDate);

if(!datebox_isshow) {

prepareCalendar();

document.all['div_datebox'].style.top =
window.event.srcElement.offsetTop +
window.event.srcElement.offsetHeight;

document.all['div_datebox'].style.left =
window.event.srcElement.offsetLeft;

document.all['div_datebox'].style.visibility = 'visible';
datebox_isshow = true;

} else {

if(datebox_isshow) {
document.all['div_datebox'].style.visibility = 'hidden';
datebox_isshow = false;
}
}

return false;
}

function clickMonthLeft() {

if ((get_normalYear(showDate) == 1990) &&
(showDate.getMonth() == 0)) return false;

showDate.setMonth(showDate.getMonth() - 1);

prepareCalendar();

return false;
}

function clickMonthRight() {

if ((get_normalYear(showDate) == 2020) &&
(showDate.getMonth() == 11)) return;

showDate.setMonth(showDate.getMonth() + 1);

prepareCalendar();

return false;
}

function clickYear() {

showDate.setYear(selectYear.value);

prepareCalendar();

return false;
}

function clickMonth() {

showDate.setMonth(selectMount.value);

prepareCalendar();

return false;
}

function clickDay(y, m, d) {
alert(y + ' ' + m + ' ' + d);
}

function prepareCalendar() {

var inner_showDate = new Date(showDate);

var showMonth = inner_showDate.getMonth();

var content =
'<input id=button_datebox type=button value="<<<" onclick="return clickMonthLeft();">';

content += '<select name=selectMount onchange="return clickMonth();">';
var index;
for (index = 0; index < month_label.length; index++) {

content += '<option value=' + index;

if (showMonth == index) content += ' selected';
content += '>' + month_label[index] + '</option>';

}
content += '</select>';

content += '<select name=selectYear onchange="return clickYear();">';
var index;

for (index = 1990; index <= 2020; index++) {

content += '<option value=' + index;

if (get_normalYear(inner_showDate) == index) content += ' selected';
content += '>' + index + '</option>';

}
content += '</select>';

content +=
'<input id=button_datebox type=button value=">>>" onclick="return clickMonthRight();">';

content += '<table bgcolor=#eeeeee>';

content += '<tr>';

for (index = 0; index < 7; index++) {
switch(index) {
case 0: content += '<td>Пн</td>'; break;
case 1: content += '<td>Вт</td>'; break;
case 2: content += '<td>Ср</td>'; break;
case 3: content += '<td>Чт</td>'; break;
case 4: content += '<td>Пт</td>'; break;
case 5: content += '<td style="color:red">Сб</td>'; break;
case 6: content += '<td style="color:red">Вс</td>'; break;
}
}

content += '</tr>';

inner_showDate.setDate(1);
inner_showDate.setDate(1 - get_normalDay(inner_showDate));

var style_content = '';

do {
content += '<tr>';

for (index = 0; index < 7; index++) {

style_content = '';

if (inner_showDate.getMonth() == showMonth) {

if (compareDate(currentDate, inner_showDate))
style_content += 'background-color:green;';
else
if (compareDate(workDate, inner_showDate))
style_content += 'background-color:blue;';

if (get_normalDay(inner_showDate) == 5 ||
get_normalDay(inner_showDate) == 6)
style_content += 'color:red;';

if (style_content.length != 0)
style_content = ' style="' + style_content + '"';
}

content += '<td' + style_content + '>';

if (inner_showDate.getMonth() == showMonth)
content +=
'<a href="" onclick="clickDay(' +
get_normalYear(inner_showDate) + ',' +
inner_showDate.getMonth() + ',' +
inner_showDate.getDate() + '); return false;">' +
inner_showDate.getDate() +
'</a>';
else
content += '&nbsp;';

content += '</td>';

inner_showDate.setDate(inner_showDate.getDate() + 1);
}

content += '</tr>';

} while (inner_showDate.getMonth() == showMonth);

content += '</table>';

document.all.div_datebox.innerHTML = content;
}

</script>

<div id=div_datebox></div>


<br>
<br>
<br>
<br>
<br>
<center>
<input id=button_datebox type=button value=213 onmousedown="clickDatebox();">
<center>