var tables = document.getElementsByTagName("table");
for ( var t = 0; t < tables.length; t++ ) {
  if (tables[t].id == 'clients'){
  var rows = tables[t].getElementsByTagName("tr");
  for ( var i = 0; i < rows.length; i += 2 )
    if ( !/(^|s)odd(s|$)/.test( rows[i].className ) )
      rows[i].className += " odd";
}
}