How to do date/time arithmetic?

Tinderbox Tasks
3

I concur with @PaulWalters that the best approach is an interval as it is specifically designed for (intervals of) time. but, if you don’t like/understand those, can you use a Number attribute here? Yes. Let’s investigate…

$EndDate=$StartDate+10 minutes

is better written as

$EndDate=$StartDate+"10 minutes";

But even better is:

$EndDate=date($StartDate +"10 minutes");

Now if Number-type attribute $Duration has a value of 10 this achieves the same as above)

$EndDate=date($StartDate +($Duration +" minutes"));

The extra parentheses are to ensure Tinderbox combines $Duration with the literal string “minutes” which can only reconcile to a string which then works inside date() for interval addition/subtraction.

(Tested in v7.1.0)