diff --git a/helpful.js b/helpful.js
index d39db91..5c47cb7 100644
--- a/helpful.js
+++ b/helpful.js
@@ -31,6 +31,31 @@
 		return duplicated;
 	}
 
+
+	helpful.deepDuplicateArray = function(array) {
+	if (array == null) {
+		return [];
+	}
+
+	let duplicated = helpful.duplicateArray(array); // flache Kopie
+	for (let i = 0; i < duplicated.length; i++) {
+		if (Array.isArray(duplicated[i])) {
+			duplicated[i] = helpful.deepDuplicateArray(duplicated[i]); // Rekursion bei Subarrays
+		}
+	}
+	return duplicated;
+}
+
+	console.log(duplicatedArray);
+
+testArray[2][0] = 99;
+console.log(testArray); // Sollte [1, 2, [99, 4], 5] ausgeben
+console.log(duplicatedArray);
+	
+	console.log(helpful.deepDuplicateArray(null));
+
+	
+
 	helpful.differenceOfArrays = function(array1, array2) {
 		if(array1 == null || array2 == null) {
 			return [];