WordPress 如何判断访客是否爬虫蜘蛛？

WordPress「PHP」如何判断访客是否爬虫蜘蛛？搜索引擎蜘蛛都有自己特有标识，可以通过 HTTP_USER_AGENT 来判断是否是蜘蛛，代码提取、修改自 WP-PostViews 插件。

isCrawler 代码如下：

if ( !function_exists( 'isCrawler' ) ) {
  //https://xuv.cc/ 提取自 WP-PostViews 插件 https://wordpress.org/plugins/wp-postviews
  function isCrawler() {
    $bots = array(
      'Google Bot' => 'google'
      , 'MSN' => 'msnbot'
      , 'Alex' => 'ia_archiver'
      , 'Lycos' => 'lycos'
      , 'Ask Jeeves' => 'jeeves'
      , 'Altavista' => 'scooter'
      , 'AllTheWeb' => 'fast-webcrawler'
      , 'Inktomi' => 'slurp@inktomi'
      , 'Turnitin.com' => 'turnitinbot'
      , 'Technorati' => 'technorati'
      , 'Yahoo' => 'yahoo'
      , 'Findexa' => 'findexa'
      , 'NextLinks' => 'findlinks'
      , 'Gais' => 'gaisbo'
      , 'WiseNut' => 'zyborg'
      , 'WhoisSource' => 'surveybot'
      , 'Bloglines' => 'bloglines'
      , 'BlogSearch' => 'blogsearch'
      , 'PubSub' => 'pubsub'
      , 'Syndic8' => 'syndic8'
      , 'RadioUserland' => 'userland'
      , 'Gigabot' => 'gigabot'
      , 'Become.com' => 'become.com'
      , 'Baidu' => 'baiduspider'
      , 'so.com' => '360spider'
      , 'Sogou' => 'spider'
      , 'soso.com' => 'sosospider'
      , 'Yandex' => 'yandex'
    );
    $useragent = isset( $_SERVER['HTTP_USER_AGENT'] ) ? $_SERVER['HTTP_USER_AGENT'] : '';
    foreach ( $bots as $name => $lookfor ) {
      if ( ! empty( $useragent ) && ( false !== stripos( $useragent, $lookfor ) ) ) {
        return true;
      }
    }
    return false;
  }
}

折腾 WordPress 主题可能用得上，直接使用 isCrawler() 判断，爬虫返回 true，否则 false。