你可以使用jQuery Simply Countable plugin 并将其附加到摘录输入。

Limit_Excerpt_Words::on_load();

class Limit_Excerpt_Words {

    static function on_load() {

        add_action( \'admin_enqueue_scripts\', array( __CLASS__, \'admin_enqueue_scripts\' ) );

    }

    static function admin_enqueue_scripts() {

        global $hook_suffix;

        if ( \'post.php\' == $hook_suffix || \'post-new.php\' == $hook_suffix ) {

            wp_enqueue_script( \'jquery-simply-countable\', plugins_url( \'/jquery.simplyCountable.js\', __FILE__ ), array( \'jquery\' ), \'0.4.2\', true );

            add_action( \'admin_print_footer_scripts\', array( __CLASS__, \'admin_print_footer_scripts\' ) );
        }
    }

    static function admin_print_footer_scripts() {

        ?>
  <script type=\'text/javascript\'>
      jQuery(document).ready(function ($) {

          $(\'#excerpt\').simplyCountable({
              countType:\'words\', maxCount:5, strictMax:true
          });

      });
  </script>

  <span id="counter" style="display:none;"></span><!-- needs counter to work -->
    <?php
    }
}