&lt;script language=&quot;javascript&quot; type=&quot;text/javascript&quot;&gt;<br>
function chkCheck(fChecked)<br>
{<br>
document.getElementById(&quot;chk&quot;).style.visibility = fChecked ? &quot;&quot; 
: &quot;hidden&quot;;<br>
}<br>
&lt;/script&gt;
<p>&lt;form name=&quot;form1&quot; method=&quot;post&quot; action=&quot;&quot;&gt;<br>
  <br>
  &lt;input type=&quot;checkbox&quot; name=&quot;checkbox1&quot; onClick=&quot;chkCheck(this.checked);&quot;&gt;&lt;br&gt;</p>
<p> &lt;input type=&quot;text&quot; name=&quot;text1&quot; id=&quot;chk&quot; 
  style=&quot;visibility:hidden;&quot; &gt;<br>
  <br>
  &lt;/form&gt;</p>