title: JavaScript not working for hiding and showing of textboxes
body: <p>here is my javascript code:</p>
  
  <pre><code>function htmlshw(){
      document.getElementById('ht').style.display = "visible";
      document.getElementById('jq').style.display = "none";
      document.getElementById('sc').style.display = "none";
  }
  
  function jqshw(){
      document.getElementById('ht').style.display = "none";
      document.getElementById('jq').style.display = "visible";
      document.getElementById('sc').style.display = "none";
  }
  
  function csshw(){
      document.getElementById('ht').style.display = "none";
      document.getElementById('jq').style.display = "none";
      document.getElementById('sc').style.display = "visible";
  }
  </code></pre>
  
  <p>This code is to hide and show the textboxes along with I have a HTML code in PHP page as below</p>
  
  <pre><code>&lt;body&gt;
  &lt;img src="/code.png" id="flip" onclick="showbox()" style="left: 0px; top: 20%; position: fixed; z-index: 99999;"&gt;&lt;/img&gt;
  &lt;section id="codebox" &gt;
  &lt;form action="/code.php" method="send" &gt;
  &lt;table&gt;
  &lt;tr&gt;
  &lt;button onclick="javascript:htmlshw()"&gt;HTML&lt;/button&gt;
  &lt;button onclick="javascript:csshw()"&gt;CSS&lt;/button&gt;
  &lt;button onclick="javascript:jqshw()"&gt;JS&lt;/button&gt;
  &lt;/tr&gt;
  &lt;tr class="c"&gt;
      &lt;section id="ht" class='hm'style="display: block;"&gt; 
      &lt;textarea type="text" name="HTML" &gt;&lt;?php echo $_REQUEST['HTML']; ?&gt;&lt;/textarea&gt;
      &lt;/section&gt;
  &lt;/tr&gt;
  &lt;tr class="c"&gt;
      &lt;section id="sc" class='cs' style="display: none;"&gt; 
      &lt;textarea type="text" name="CSS" &gt;&lt;?php echo $_REQUEST['CSS']; ?&gt;&lt;/textarea&gt;
      &lt;/section&gt;
  &lt;/tr&gt;
  &lt;tr class="c"&gt;
      &lt;section id="jq" class='jq' style="display: none;"&gt; 
      &lt;textarea type="text" name="JS" &gt;&lt;?php echo $_REQUEST['JS']; ?&gt;&lt;/textarea&gt;
      &lt;/section&gt;
  &lt;/tr&gt;
      &lt;input type="submit" value="Compile" style="position: fixed; right: 0px; top: 10px; z-index: 999999; "&gt;&lt;/input&gt;
  &lt;/table&gt;
  &lt;/form&gt;
  &lt;/section&gt;
  
  &lt;section id="result"&gt;
  &lt;?php echo $_REQUEST['HTML']; ?&gt;
  &lt;/section&gt;
  
  &lt;/body&gt;
  </code></pre>
  
  <p>According to design, I have placed the 3 buttons with assigning respective functions but it won't seems to be working. Is there any technical reason behind it?</p>