What we are going to do is get a reference of the countdown array and fill it with decrementing numbers with the help of setInterval.
We are accessing countdown through the vm variable we set in the line vm.countdown.push(counter--), so our list will get updated every time we add a new number to the array.
This code is very simple, just note that we must use the push function to add elements to the array. Adding elements with the square brackets notation will not work:
vm.countdown[counter] = counter-- // this won't work
The array will get updated, but this way of assignment will skip Vue's reactive system due to how JavaScript is implemented.
