use the string replace's method the resolve the int and double problem.

replace the generate code's num to int.

lib/json_generator.dart

@@ -50,8 +50,9 @@ void main() async {
   ButtonElement formatButton = querySelector("#format");
   formatButton.onClick.listen((click) {
     String pretty;
+    pretty = convertJsonString(jsonInput.value);
     try {
-      pretty = formatJson(jsonInput.value);
+      pretty = formatJson(pretty);
     } on Exception {
       return;
     }