使用Javascript获取工作日

我想在两个约会之间得到工作日.
示例：stdate = 28/10/2011 and endate = 04/11/2011.这应该是6个工作日,但它只给5天.

var workingdays = 0;
var weekday     = new Array(7);
weekday[0]="Sunday";
weekdaY[1]="Monday";
weekdaY[2]="Tuesday";
weekdaY[3]="Wednesday";
weekdaY[4]="Thursday";
weekday[5]="Friday";
weekdaY[6]="Saturday";

while (stdate <= endatE) 
{
    var day = weekdaY[stdate.getDay()];
    if(day != "Saturday" && day != "Sunday") 
    {
        workingdays++; 
    }
    console.log(weekdaY[stdate.getDay()]);
    stdate = new Date(stdate.getTime() + 86400000); 
}

控制台日志显示以下结果.

Friday
Saturday
Sunday
Sunday
Monday
Tuesday
Wednesday
Thursday

由于某种原因,周日出现两次.任何帮助,将不胜感激.

stdate = new Date(stdate.getFullYear(),stdate.getMonth(),stdate.getDate() + 1);