How to update a value based on previous value in an array of objects?

I am trying to update every current value based on the previous value of another property. Actually, I need to do the task with dates, but just to keep it simple, I’ll explain my problem with simple numbers. I have Start, which is 1. Stop, which is already defined End Duration, which is already defined… Read More How to update a value based on previous value in an array of objects?