Adding service worker cache

src/pages/index/index.js

@@ -1 +1,2 @@
 import '../../style.css';
+import '../../service-worker';

src/service-worker.js

@@ -0,0 +1,11 @@
+if ('serviceWorker' in navigator && process.env.NODE_ENV === 'production') {
+  window.addEventListener('load', () => {
+    navigator.serviceWorker.register('/sw.js')
+      .then(registration => {
+        console.log('SW registered:', registration);
+      })
+      .catch(registrationError => {
+        console.log('SW registration failed:', registrationError);
+      });
+  });
+}