auto save left input json

lib/json_generator.dart

@@ -3,6 +3,7 @@ import 'dart:convert';
 import 'dart:html';
 
 import 'package:json2dart_serialization/generator.dart';
+import 'package:json2dart_serialization/storage.dart';
 
 String entityName = null;
 
@@ -24,12 +25,12 @@ const defaultValue = "";
 
 void main() async {
   isChinese = await _isChinese();
-
+  var dataHelper = CookieHelper();
   TextAreaElement jsonInput = querySelector("#json");
-  jsonInput.value = defaultValue;
+  jsonInput.value = dataHelper.loadJsonString();
 
   jsonInput.onInput.listen((event) {
-    // print(jsonInput.value);
+    dataHelper.saveJsonString(jsonInput.value);
     refreshData();
   });
 

lib/storage.dart

@@ -0,0 +1,15 @@
+import 'dart:html';
+
+class CookieHelper {
+  String loadJsonString() {
+    var storage = window.localStorage;
+    if (!storage.containsKey("json")) {
+      return "";
+    }
+    return window.localStorage["json"];
+  }
+
+  void saveJsonString(String jsonString) {
+    window.localStorage.addAll({"json": jsonString});
+  }
+}