<input type="text" name="author" id="author" value="<?php echo $comment_author; ?>" tabindex="1" />

/**
 * 设定控件的显示风格
 * @param id    控件的 ID
 * @param status  控件的显示状态 (显示时为 '', 隐藏时为 'none')
 */
function setStyleDisplay(id, status) {
 document.getElementById(id).style.display = status;
}

<!-- 有资料的访客 -->
<?php if ( $comment_author != "" ) : ?>
 <!--
 转换显示状态用的 JavaScript
 Q1: 为什么这段代码放在这里呢?
 A1: 因为只有当访客有资料时, 它才被用上, 这样可以减少无资料访客下载页面时的开销.
 Q2: 为什么不用外部文件将 JavaScript 放起来? 也许那样维护起来更方便.
 A2: 因为它只在这个地方用到了. 而且加载文件的数量也会影响页面下载速度, 为了这么点字节的代码, 不值得新开一个文件.
 -->
 <script type="text/javascript">function setStyleDisplay(id, status){document.getElementById(id).style.display = status;}</script>
 <div class="form_row small">
 <!-- 访客昵称 (随便欢迎一下) -->
 <?php printf(__('Welcome back <strong>%s</strong>.'), $comment_author) ?>
 
 <!-- 更改按钮 (点击后: 隐藏更改按钮, 显示取消按钮, 显示资料输入框) -->
 <span id="show_author_info"><a href="javascript:setStyleDisplay('author_info','');setStyleDisplay('show_author_info','none');setStyleDisplay('hide_author_info','');"><?php _e('Change »'); ?></a></span>
 
 <!-- 取消按钮 (点击后: 显示更改按钮, 隐藏取消按钮, 隐藏资料输入框) -->
 <span id="hide_author_info"><a href="javascript:setStyleDisplay('author_info','none');setStyleDisplay('show_author_info','');setStyleDisplay('hide_author_info','none');"><?php _e('Close »'); ?></a></span>
 </div>
<?php endif; ?>
 
<!-- 资料输入框 -->
<div id="author_info">
 <div class="form_row">
 <input type="text" name="author" id="author" value="<?php echo $comment_author; ?>" tabindex="1" />
 <label for="author" class="small"><?php _e('Name'); ?> <?php if ($req) _e('(required)'); ?></label>
 </div>
 <div class="form_row">
 <input type="text" name="email" id="email" value="<?php echo $comment_author_email; ?>" tabindex="2" />
 <label for="email" class="small"><?php _e('E-Mail (will not be published)');?> <?php if ($req) _e('(required)'); ?></label>
 </div>
 <div class="form_row">
 <input type="text" name="url" id="url" value="<?php echo $comment_author_url; ?>" tabindex="3" />
 <label for="url" class="small"><?php _e('Website'); ?></label>
 </div>
 
</div>
 
<!-- 有资料的访客 -->
<?php if ( $comment_author != "" ) : ?>
 <!-- 隐藏取消按钮, 隐藏资料输入框 -->
 <script type="text/javascript">setStyleDisplay('hide_author_info','none');setStyleDisplay('author_info','none');</script>
<?php endif; ?>

>>> document.cookie
"comment_author_bbfa5b726c6b7a9cf3cda9370be3ee91=helloworld; comment_author_email_bbfa5b726c6b7a9cf3cda9370be3ee91=dangoakachan%40gmail.com; comment_author_url_bbfa5b726c6b7a9cf3cda9370be3ee91=http%3A%2F%2Fexample.com"

>>> import hashlib
>>> hashlib.md5('http://localhost/wordpress').hexdigest()
'bbfa5b726c6b7a9cf3cda9370be3ee91'

if (!is_user_logged_in() && !empty($comment_author)) {
...
}

if (!is_user_logged_in() && !empty($comment_author)) {
  $welcome_login = '<p id="welcome-login"><span>欢迎回来, <strong>' . $comment_author . '</strong>.</span>';
  $welcome_login .= ' <span id="toggle-author"><u>更改</u> <i class="icon-signout"></i></span></p>';

  $comments_args['comment_field'] = '</div>' . $comments_args['comment_field'];
  $comments_args['comment_notes_before'] = $welcome_login . '<div id="author-info" class="hide">';
}

/* Toggle comment user */
$('#comments').on('click', '#toggle-author', function () { 
  $('#author-info').slideToggle(function () { 
    if ($(this).is(':hidden')) {
      /* Update author name in the welcome messages */
      $('#welcome-login strong').html($('#author').val());

      /* Update the toggle action name */
      $('#toggle-author u').html('更改');
    } else {
      /* Update the toggle action name */
      $('#toggle-author u').html('隐藏');
    }  
  }); 
});