diff --git a/js/add.js b/js/add.js
new file mode 100644
index 0000000..c28a419
--- /dev/null
+++ b/js/add.js
@@ -0,0 +1,9 @@
+
+  
+  function add(x, y) {
+    return x + y;
+    console.log('add');
+  }
+  
+
+  
\ No newline at end of file
diff --git a/js/hello_world.js b/js/hello_world.js
index 17ef608..7075136 100644
--- a/js/hello_world.js
+++ b/js/hello_world.js
@@ -1,10 +1,10 @@
 function main() {
   console.log('Hello world!');
-  console.log('a() ===', a());
+  console.log('a() ===', bla(5,6));
 }
 
-function a() {
-  return 1 + 1;
+function bla(x, y) {
+  return x * y;
 }
 
 if (require.main === module) {
diff --git a/js/sub.js b/js/sub.js
new file mode 100644
index 0000000..bdee2c6
--- /dev/null
+++ b/js/sub.js
@@ -0,0 +1,8 @@
+
+  
+  function sub(x, y) {
+    return x - y;
+  }
+  
+
+  
\ No newline at end of file