Implemented suggesting improvements

test/permutations/permutations.js

@@ -0,0 +1,14 @@
+const permutations = arr => {
+if (arr.length <= 2) return arr.length === 2 ? [arr, [arr[1], arr[0]]] : arr;
+return arr.reduce(
+(acc, item, i) =>
+acc.concat(
+permutations([...arr.slice(0, i), ...arr.slice(i + 1)]).map(val => [
+item,
+...val,
+])
+),
+[]
+);
+};
+module.exports = permutations;