Jak nastavit focus pro prvek u manualne vytvareneho formulare

Mam jednoduchou sablonu:

 {control loginForm begin}

 {foreach $flashes as $flash}
  <p class="flash-message">{$flash->message}</p>
 {/foreach}

 {assign errors => $control['loginForm']->errors}
  <p class="error" n:if="$errors" n:foreach="$errors as $error">{$error}</p>

  <table>
    <tr>
      <td class="upper" colspan="2">
        <b><font size='1px'>::: LOGIN :::</font></b>
      </td>
    </tr>
    <tr>
      <td colspan="2" height="5"></td>
    </tr>
    <tr>
      <td class="labels">
        {$control['loginForm']['username']->label}
      </td>
      <td>
        {$control['loginForm']['username']->control}
      </td>
    </tr>
    <tr>
      <td class="labels">
        {$control['loginForm']['password']->label}
      </td>
      <td>
        {$control['loginForm']['password']->control}
      </td>
    </tr>
    <tr>
      <td colspan="2" height="5"></td>
    </tr>
    <tr>
      <td class="lower" colspan="2">
        <input type="submit" style="margin-left:230px;" value="Submit">
      </td>
    </tr>
  </table>
  {control loginForm end}

username, kteremu bych chtel nastavit focus se prevede na toto HTML:

<input type="text" class="text" name="username" id="frmloginForm-username" value="" />

Rad bych nastavil focus jednoduse takto: document.getElementById(„<id>“) .. nicmene nevim, jakym zpusobem zjistit soucasne ID (tj. frmloginForm-username – natvrdo to davat do JS nechci), pripadne jak ho zmenit.

Predem diky za odpoved!