Ваша HTML-разметка неверна.
var z="<table>
<td>Blog title and date<br><hr></td>
<tr>
<td>A very long string consisting of many paragraphs, say, a blog</td></table>";
Этот код такой:
<table>
<td>Blog title and date<br><hr></td>
<tr>
<td>A very long string consisting of many paragraphs, say, a blog</td>
</table>
Должно быть:
<table>
<tr>
<td>Blog title and date<br><hr></td>
</tr>
<tr>
<td>A very long string consisting of many paragraphs, say, a blog</td>
</tr>
</table>