diff --git a/js/nesting b/js/nesting
new file mode 100644
index 0000000..9a9c4de
--- /dev/null
+++ b/js/nesting
@@ -0,0 +1,8 @@
+function solution(S) {
+    let count = 0
+    for (let i=0; i<S.length; i++) {
+        if (S[i] == '(') count++
+        else if (--count < 0) return 0
+    }
+    return count === 0 ? 1 : 0
+}