debug googlebot

debug_googlebot.js

<script>
  if (window && window.navigator && /googlebot/i.test(window.navigator.userAgent)) {
    var debug = function(key, value) {
      var writeToBody = function() { document.body.setAttribute('data-' + key, value); };
      if (document.body) writeToBody();
      else window.addEventListener('DOMContentLoaded', writeToBody, false);
    };

    debug('googlebot', '1');

    window.onerror = function(message, url, line, column, error) {
      var fullMessage = JSON.stringify({
        message: message,
        url:     url,
        line:    line,
        column:  column,
        stack:   (error && error.stack)
      });

      var randomNumber = Math.ceil(Math.random() * 1000000);

      debug('googlebot-err-' + randomNumber, fullMessage);
    };
  };
</script>