使用HTML和HTML中的正则表达式匹配来定义类名

I want create an dynamic HTML page were the class name is defined by the php program

My code:

<?php

 error_reporting(E_ALL);
 ini_set("display_errors", 1);
?>
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function hideTd(){
    var elements = document.getElementsByClassName("ca");
    for(var i = 0, length = elements.length; i < length; i++) {
          elements[i].style.display = 'none';
    }
  }
</script>
</head>
<body onload="hideTd()">
<select name="retailerselect" id="retailerselect" onchange="retailerSelect()" width: 66px;> 
  <option selected="selected" size="10" >--SELECT--</option>
  <option class="ca">hi</option>
  <option class="ca">this</option>  
          <?php $connect = " yes-ad";?>
                <option class="<?php echo $connect;?>"> <?php echo $connect;?> </option>

  </select>
 </body>
  </html>

I the HTML script i would have hide the value of option tag in the class "ca"

Input:

$connect:"yes-ad"

Output:

class="ad" value in the option ="yes-ad"

Sorry if my script is wrong i am a newbie in HTML or is there any other way to do this

Edit: Simplified the script

The Output iam getting now

enter image description here

I want it to show yes-ad with its class

<?php

 error_reporting(E_ALL);
 ini_set("display_errors", 1);
?>
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function hideTd(){
    var elements = document.getElementsByClassName("ca");
    for(var i = 0, length = elements.length; i < length; i++) {
          elements[i].style.display = 'none';
    }
  }
</script>
</head>
<body onload="hideTd()">
<select name="retailerselect" id="retailerselect" onchange="retailerSelect()" width: 66px;> 
  <option selected="selected" size="10" >--SELECT--</option>
  <option class="ca">hi</option>
  <option class="ca">this</option>  
          <?php $connect = " yes-ad";?>
                <option class="<?php echo $connect;?>"> <?php echo $connect;?> </option>

  </select>
 </body>
  </html>

The php code is wrong. There should not be { and } .Just remove them.

And to change the classname, just do like this:

<option class="<?php echo $connect;?>">....</option>