title: .each() > $(this).find().eq().html() is null
body: <p>Why don't work?</p>
  
  <pre><code>var str;
  
  $('table tr').each(function() {
      str = $(this).find('td').eq(6).html().trim().substring(10, 20);
      $(this).find('td').eq(6).text(str);
  });
  </code></pre>
  
  <p>Need write in all 6th  trim+substring+another_string_action with same value.</p>
  
  <p>Firebug write error: <strong>$(this).find("td").eq(6).html() is null</strong></p>