function getDeliveryDateObj(businessDaysLeftForDelivery) {
  var now = new Date();
  var dayOfTheWeek = now.getDay();
  var calendarDays = businessDaysLeftForDelivery;
  var deliveryDay = dayOfTheWeek + businessDaysLeftForDelivery;
  if (deliveryDay >= 6) {
    //deduct this-week days
    businessDaysLeftForDelivery -= 6 - dayOfTheWeek;
    //count this coming weekend
    calendarDays += 2;
    //how many whole weeks?
    deliveryWeeks = Math.floor(businessDaysLeftForDelivery / 5);
    //two days per weekend per week
    calendarDays += deliveryWeeks * 2;
  }
  now.setTime(now.getTime() + calendarDays * 24 * 60 * 60 * 1000);
  return now;
}

The algorithm is to add the weekend days to the number of business days, yielding the target delivery date. The variable calendarDays denotes the number of calendar days. We update it as we go along. The first line creates today's Date object:

var now = new Date();

var dayOfTheWeek = now.getDay();

var calendarDays = businessDaysLeftForDelivery;

var deliveryDay = dayOfTheWeek + businessDaysLeftForDelivery;

if (deliveryDay >= 6) {

//deduct this-week days
businessDaysLeftForDelivery -= 6 - dayOfTheWeek;

//count this coming weekend
calendarDays += 2;

//how many whole weeks?
deliveryWeeks = Math.floor(businessDaysLeftForDelivery / 5);

//two days per weekend per week
calendarDays += deliveryWeeks * 2;

now.setTime(now.getTime() + calendarDays * 24 * 60 * 60 * 1000);

People who read this tip also read these tips:

• Implementing Relative Times
• getFullYear() vs. getYear()
• Hiding Popups
• What Day were you Born on?
• GMT and Local Dates