title: How can I get all text node in document fragment?
body: <p>I get the user selected text:</p>
  
  <pre><code>var selection = window.getSelection();
  var selectRange = selection.getRangeAt(0);
  
  var content = selectRange.cloneContents(); // DocumentFragment
  </code></pre>
  
  <p>How can I get the <code>textNode</code> in the <code>DocumentFragment</code> content?</p>