$doTask = "if (document.adminForm.boxchecked.value==0){
    alert('$message');
}
 else {
      Joomla.submitbutton('$task')
 }";

$i18n_text = JText::_($text);
$class = JButton::fetchIconClass($name);


$html = "<a href="javascript: void();" onclick="$doTask" class="toolbar">n";
$html .= "<span class="$class">n";
$html .= "</span>n";
$html .= "$i18n_textn";
$html .= "</a>n";

else {
   if(confirm('Are you sure you want to delete ?'))
      Joomla.submitbutton('$task');
}