javascript判断日期是否合法

function IsDate(str)
{
arr = str.split("-");
if(arr.length == 3)
{
intYear = parseInt(arr[0],10);
intMonth = parseInt(arr[1],10);
intDay = parseInt(arr[2],10);
if(isNaN(intYear) || isNaN(intMonth) || isNaN(intDay))
{
return false;
}
if(intYear > 2100 || intYear < 1900 || intMonth > 12 || intMonth < 0 || intDay > 31 || intDay < 0)
{
return false;
}
if((intMonth == 4 || intMonth == 6 || intMonth == 9 || intMonth == 11) && intDay > 30)
{
return false;
}
if(intYear % 100 == 0 && intYear % 400 || intYear % 100 && intYear % 4 == 0)
{
if(intDay > 29)
return false;
}
else
{
if(intDay > 28)
return false;
}
return true;

}
return false;
}