[рони]

greenwar,
вариант ...

<style>
div {
  display:none;
  border:1px solid black;
  width:0px;
}
</style>
<div id='FB_div'></div>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>

<script>
$('#FB_div').html('<table><tr><td>some_html_from_data</td></tr></table>');
$('#FB_div').show();
alert($('#FB_div')[0].scrollWidth);
</script>