diff --git a/codewars/7kyu/sum-of-a-nested-list/koronya.js b/codewars/7kyu/sum-of-a-nested-list/koronya.js
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+// [JS][7kyu] Sum of a nested list
+// sum-of-a-nested-list
+// https://www.codewars.com/kata/5a15a4db06d5b6d33c000018/train/javascript
+
+// const sumNested = (arr) => {
+//   return arr.flat().reduce((acc, item) => acc + (Array.isArray(item) ? sumNested(item) : item), 0)
+// }
+const sumNested = (arr) => arr.flat(Infinity).reduce((acc, item) => acc + item, 0)
+
+sumNested([1]) === 1
+sumNested([1, 2, 3, 4]) === 10
+sumNested([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) === 55
+
+sumNested([]) === 0
+
+sumNested([[1], []]) === 1
+sumNested([[1, 2, 3, 4]]) === 10
+
+sumNested([1, [1], [[1]], [[[1]]]]) === 4
+sumNested([1, [1], [1, [1]], [1, [1], [1, [1]]]]) === 8
+
+sumNested([[[[], [], [[[[[[[[[[]]]]]]]]]]], [], [], [[[], [[]]]]], []]) === 0