Storyboard Control Functions

I have managed to get this to work pretty much as I want but there are still issues with the control functions.

On this page I am attempting to break-out the control coding so that I can debug it in isolation.

The script on this page contains the function plusSlides(). The variables that control the next and previous menu items for the storyboard are controlled by the function.

The value of index of the displayed slide is displayed in the button "Like" as on this page. The button is called "interval".

I have managed to get the "Next" button to work and loop around to the beginning.

Controls:

The value of myIndex: .