title: Google scripts, change text in Form.html from Code.gs
body: <p>In my Google Script I have 2 files: Form.html and Code.gs
  When user click button in Form.html, the script start code in Code.gs, but I need inform user about process. 
  How I can change text in Form.html from Code.gs?</p>
  
  <p>Form.html crate in  Code.gs by this function:</p>
  
  <pre><code>function showSidebar() {
    var ui = HtmlService.createHtmlOutputFromFile('Form')
        .setTitle('Report');
    SpreadsheetApp.getUi().showSidebar(ui);
  }
  </code></pre>
  
  <p>And Form.html have</p>
  
  <pre><code>&lt;div id="report"&gt;&lt;/div&gt;
  </code></pre>
  
  <p>For status report.</p>