title: Get return value of function javascript on webbrowser
body: <p>I have a javascript function:</p>
  
  <pre><code>function getData(){
     return document.getElementById("xx").value;
  }
  </code></pre>
  
  <p>I use <code>HtmlElement</code> to append code in html and use webbrowser <code>invokescript</code> to run function <code>getData()</code>.</p>
  
  <p>I want to get return value of <code>getData()</code> and show it on messageBox.</p>