WPF中使用GetElementById，显示“object”未包含“getElementById”的定义

Question

private void goNavigateButton_Click(object sender, RoutedEventArgs e)
{
// Get URI to navigate to

Uri uri = new Uri(this.addressTextBox.Text, UriKind.RelativeOrAbsolute);

        // Only absolute URIs can be navigated to  
        if (!uri.IsAbsoluteUri)
        {
            MessageBox.Show("The Address URI must be absolute eg 'http://www.microsoft.com'");
            return;
        }

        // Navigate to the desired URL by calling the .Navigate method  
        WebBrowser1.Navigate(uri);

            string s = WebBrowser1.Document.getElementById("txt1").Value;


    }

Answer 1

dynamic doc = WebBrowser1.Document;
string s = doc.getElementById("txt1").Value;