Split app.js in to smaller chunks

public/js/auth.js

@@ -0,0 +1,25 @@
+export function checkSession() {
+    return fetch('/check-session')
+        .then(response => {
+            if (!response.ok) {
+                throw new Error('Network response was not ok');
+            }
+            return response.json();
+        });
+}
+
+export function login(username, password) {
+    return fetch('/login', {
+        method: 'POST',
+        headers: {
+            'Content-Type': 'application/json',
+            'Authorization': 'Basic ' + btoa(username + ':' + password)
+        }
+    });
+}
+
+export function logout() {
+    return fetch('/logout', {
+        method: 'POST'
+    });
+}