foo.cs

        private void RunSerializedScript(string script, string sourceUrl)
        {
            var localFolder = ApplicationData.Current.LocalFolder;
            var binFile = "ReactNativeSerializedBundle.bin";
            var binPath = Path.Combine(localFolder.Path, binFile);

            try
            {
                if(!EnsureSerializedScriptAsync(script, binFile).Result)
                {
                    Native.ThrowIfError((JavaScriptErrorCode)_executor.SerializeScriptFromFile(script, binPath));
                }

                var result = _executor.RunSerializedScriptFromFile(binPath, script, sourceUrl);
                Native.ThrowIfError((JavaScriptErrorCode)result.ErrorCode);
            }
            catch (JavaScriptScriptException ex)
            {
                var jsonError = JavaScriptValueToJTokenConverter.Convert(ex.Error);
                var message = jsonError.Value<string>("message");
                var stackTrace = jsonError.Value<string>("stack");
                throw new Modules.Core.JavaScriptException(message ?? ex.Message, stackTrace, ex);
            }
        }
        
        private static async Task<bool> EnsureSerializedScriptAsync(string scriptFile, string binFile)
        {
            var localFolder = ApplicationData.Current.LocalFolder;

            var scriptItem = await StorageFile.GetFileFromPathAsync(scriptFile);
            var scriptItemProps = await scriptItem.GetBasicPropertiesAsync();
            var item = await localFolder.TryGetItemAsync(binFile);
            if (item != null)
            {
                var props = await item.GetBasicPropertiesAsync();
                return props.DateModified > scriptItemProps.DateModified;
            }

            return false;
        }