在<head></head>标签内添加以下代码

<script type="text/javascript">
/*动态网页标题*/
var OriginTitile = document.title,
titleTime;
document.addEventListener("visibilitychange",
function() {
    if (document.hidden) {
        $('[rel="shortcut icon"]').attr("href", "favicon.ico");
        document.title = "你别走吖 Σ(っ °Д °;)っ";
        clearTimeout(titleTime)
    } else {
        $('[rel="shortcut icon"]').attr("href", "favicon.ico");
        document.title = "你可算回来了 (｡•ˇ‸ˇ•｡)" + OriginTitile;
        titleTime = setTimeout(function() {
            document.title = OriginTitile
        },
        2000)
    }
});
</script>

源码来自灵曦博客。