make git ignore generated js files

Author: Johnwook Choi

.gitignore

@@ -57,3 +57,5 @@ typings/
 # dotenv environment variables file
 .env
 
+# ignore build js files
+*.js

index.js

@@ -1,3 +1,6 @@
-module.exports = (req, res) => {
-  res.end("Welcome to Micro");
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+const handler = (_, res) => {
+    res.end("Welcome to Micro");
 };
+module.exports = handler;