Added logout function.

logout.js

@@ -0,0 +1,20 @@
+//VARIBLES
+
+let username = localStorage.getItem('username');
+
+//LOGOUT FETCH FUNCTION
+
+async function logout() {
+    let sendLogoutInfo = { "name": username }
+    fetch('/api/logout/', {
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+    },
+      body: JSON.stringify(sendRegisterInfo),
+    });
+    document.querySelector("#errormessage").innerHTML = 'Logged out.'
+    localStorage.removeItem('username')
+
+  }
+