Implement moving array pointer index.
When you have an array with index pointing to eg. selected item and this index should move.
Solutions I often saw take multiple lines and if
statements to prevent index from pointing out of an array.
However there is a one liner way.
// vector is 1 or -1 depending on user interaction
return (currentIndex + arrayLength + vector) % arrayLength;
To better illustrate I have made code sandbox example.
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