foreach($group as $i => $name){
   print'<li onclick="groups('group'.$i.'');" >'.$name.'</li>';
}

$moretags = "<script>";
$moretags .= 'function groups(grid){';
  foreach($group as $i => $name){
  $moretags .= '
  if(grid == 'group'.$i.''){
  document.getElementById('show').innerHTML = 'group'.$i.'';
  }
  ';

}


$moretags .= '</script>';

$groups = array('some', 'elements', 'here');

<script>
    var groups = <?php echo json_encode($groups); ?>;
</script>