In this example we calculate a date, based on an input date in a date control. Within the below rule, we add days based on the selected date. For example, if its Monday, we add 3 days, if it's Thursday, we add 4 days, etc. You can use this rule for assisting with date calculations. This rule also logs items to the Javascript Console as it runs for more informational purposes using output.log().

Calculate Date Based on Day of Week

// d should be whatever your date field is, otherwise leave it alone, ie: date.datefiled
var d = data.startingDate;
// Gets the Current Day of the Week from the starting Date field.
var day = d.getDay();
var actualDay;
var newDay = new Date();

if (day === 0)
{ actualDay = 'Sunday';}
else if (day == 1)
{ actualDay = 'Monday';}
else if (day == 2)
{ actualDay = 'Tuesday';}
else if (day == 3)
{ actualDay = 'Wednesday';}
else if (day == 4)
{ actualDay = 'Thursday';}
else if (day == 5)
{ actualDay = 'Friday';}
else if (day == 6)
{ actualDay = 'Saturday';}

// Here we echo the resulting day integer to console and the day of week
console.log('Today is: ' + day);
console.log('Today is: ' + actualDay);

// Here we evaluate the day and perform math to calculate the day.
if (actualDay == 'Sunday')
{
	// The +1 here adds 1 business day.  You can change the 1 to any integer to suite your calculations.
  newDay.setDate(d.getDate() + 1);
  console.log('Calculated Day is: ' + newDay);
}
// the + 3 here adds 3 days to the input date
if (actualDay == 'Monday')
{
  newDay.setDate(d.getDate() + 3);
  console.log('Calculated Day is: ' + newDay);
}
if (actualDay == 'Tuesday')
{
	// the + 3 here adds 3 days to the input date
  newDay.setDate(d.getDate() + 3);
  console.log('Calculated Day is: ' + newDay);
}
if (actualDay == 'Wednesday')
{
	// the + 3 here adds 5 days to the input date
  newDay.setDate(d.getDate() + 5);
  console.log('Calculated Day is: ' + newDay);
}
// the + 4 here adds 4  days to the input date
if (actualDay == 'Thursday')
{
	// the + 3 here adds 4  days to the input date
  newDay.setDate(d.getDate() + 4);
  console.log('Calculated Day is: ' + newDay);
}
// the + 3 here adds 3  days to the input date
if (actualDay == 'Friday')
{
  newDay.setDate(d.getDate() + 3);
  console.log('Calculated Day is: ' + newDay);
}
// the + 2 here adds 2 days to the input date
if (actualDay == 'Saturday')
{
  newDay.setDate(d.getDate() + 2);
  console.log('Calculated Day is: ' + newDay);
}

var v = newDay;

// Write the Formated Date into a text field.
value = v.getMonth()+1 + '/' + v.getDate() + '/' + v.getFullYear();

Attached to this form post is an example form.

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