js判断给定时间区间里面有几个工作日

//比较开始日期与结束日期
function countWorkDay(sDay,eDay){
var s = sDay;
var e = eDay;
var s_t_w = s.getDay(), e_t_w = e.getDay();
//相差天数
var diffDay = (e - s) / (1000 * 60 * 60 * 24) + 1;
//如果开始日期为周六或者周日 需要调整相差天数
var diffWeekDay = diffDay - (s_t_w 0?1:0)- (s_t_w 6?2:0);
//计算有几个完整的周
var weeks = Math.floor(diffWeekDay / 7); //向下整除 4/3=1;
var i = weeks*5 + (e_t_w6?5:e_t_w) + ( s_t_w >= 1 && s_t_w <= 5 ? (6-s_t_w):0);
var x = diffDay - weeks*2;
if(i<=x){
return i;
}else {
if(e_t_w6){
x=x-1;
}
return x;
}
}