problems(js): add “2649. Nested Array Generator”

Signed-off-by: Matej Focko <mfocko@redhat.com>

problems/js/nested-array-generator.js

@@ -0,0 +1,37 @@
+/**
+ * @param {Array} arr
+ * @return {Generator}
+ */
+var inorderTraversal = function*(arr) {
+    let stack = [[arr, 0]];
+
+    while (stack.length) {
+        let [arr, i] = stack.pop();
+        if (i >= arr.length) {
+            // finished with the nested array
+            continue;
+        }
+
+        // if it's a nested array
+        if (arr[i] instanceof Array) {
+            // gotta continue with the next element of the array
+            stack.push([arr, i + 1]);
+
+            // gotta start with the first element of the nested
+            stack.push([arr[i], 0]);
+
+            // yielding is done only on the elements themselves
+            continue;
+        }
+
+        yield arr[i];
+        stack.push([arr, i + 1]);
+    }
+};
+
+/**
+ * const gen = inorderTraversal([1, [2, 3]]);
+ * gen.next().value; // 1
+ * gen.next().value; // 2
+ * gen.next().value; // 3
+ */