Implemented autosave on a 5-second timer

pkgs/dartpad_ui/lib/editor/editor.dart

@@ -177,10 +177,17 @@ class _EditorWidgetState extends State<EditorWidget> implements EditorService {
   @override
   void initState() {
     super.initState();
-
+    _autosaveTimer = Timer.periodic(const Duration(seconds: 5), _autosave);
     widget.appModel.appReady.addListener(_updateEditableStatus);
   }
 
+  Timer? _autosaveTimer;
+  void _autosave([Timer? timer]) {
+    final content = codeMirror?.getDoc().getValue();
+    if (content == null) return;
+    web.window.localStorage.setItem('user_input', content);
+  }
+
   void _platformViewCreated(int id, {required bool darkMode}) {
     codeMirror = codeMirrorInstance;
 
@@ -305,6 +312,8 @@ class _EditorWidgetState extends State<EditorWidget> implements EditorService {
   @override
   void dispose() {
     listener?.cancel();
+    _autosaveTimer?.cancel();
+    _autosave();
 
     widget.appServices.registerEditorService(null);
 

pkgs/dartpad_ui/lib/execution/frame.dart

@@ -63,7 +63,7 @@ function dartPrint(message) {
     'sender': 'frame',
     'type': 'stdout',
     'message': message.toString()
-  }, '*');  
+  }, '*');
 }
 ''');
 

pkgs/dartpad_ui/lib/main.dart

@@ -15,6 +15,7 @@ import 'package:provider/provider.dart';
 import 'package:split_view/split_view.dart';
 import 'package:url_launcher/url_launcher.dart' as url_launcher;
 import 'package:vtable/vtable.dart';
+import 'package:web/web.dart' as web;
 
 import 'console.dart';
 import 'docs.dart';
@@ -277,7 +278,8 @@ class _DartPadMainPageState extends State<DartPadMainPage>
             sampleId: widget.builtinSampleId,
             flutterSampleId: widget.flutterSampleId,
             channel: widget.initialChannel,
-            fallbackSnippet: Samples.getDefault(type: 'dart'))
+            fallbackSnippet: web.window.localStorage.getItem('user_input') ??
+                Samples.getDefault(type: 'dart'))
         .then((value) {
       // Start listening for inject code messages.
       handleEmbedMessage(appServices, runOnInject: widget.runOnLoad);