drupal html5的 placeholder

function THEMENAME_form_alter( &$form, &$form_state, $form_id ) {
  if ( TRUE === in_array( $form_id, array( 'user_login', 'user_login_block') ) )
    $form['name']['#attributes']['placeholder'] = t( 'Username' );
    $form['pass']['#attributes']['placeholder'] = t( 'Password' );
}
?>

来自  https://www.drupal.org/node/1517886