1. Create a new funny_title.js file in the \themes\butterfly\source\js directory and add the following code:

     1var OriginTitle = document.title;
 2var titleTime;
 3document.addEventListener('visibilitychange', function () {
 4    if (document.hidden) {
 5        $('[rel="icon"]').attr('href', "/funny.ico");
 6        document.title = '╭(°A°`)╮ Why did you leave ~';
 7        clearTimeout(titleTime);
 8    }
 9    else {
10        $('[rel="icon"]').attr('href', "/favicon.ico");
11        document.title = '(ฅ>ω<*ฅ) Welcome back ~' + OriginTitle;
12        titleTime = setTimeout(function () {
13            document.title = OriginTitle;
14        }, 2000);
15    }
16});

  2. In the theme configuration file _config.butterfly.yml, under the inject section, add the following line in the bottom section to include the js file:

    1- <script src="/js/funny_title.js"></script>