Using The Elvis / Null Coalescing Operator To Loop Past Array Boundaries In Lucee CFML 5.3.7.47

test.cfm

<cfscript>

	letters = [ "A", "B", "C", "D", "E" ];

	linkedLetters = letters.map(
		( letter, i ) => {

			return([
				current: letter,
				// We can use the null-coalescing operator to safely wrap around the
				// bounds of an array. When the incremented / decremented index results
				// in an undefined array item, it means that we've hit a boundary
				// condition and we need to fallback to the item at the opposite end of
				// the array (either the first or last item depending on the direction).
				nextLetter: ( letters[ i + 1 ] ?: letters.first() ),
				prevLetter: ( letters[ i - 1 ] ?: letters.last() )
			]);

		}
	);

	dump( linkedLetters );

</cfscript>