在footer.php中的<?php wp_footer();?>后添加：

<script>
function runTime() {
    var d = new Date(), str = '';
    BirthDay = new Date("12/14/2020 12:01:00");
    today = new Date();
    timeold = (today.getTime() - BirthDay.getTime());
    sectimeold = timeold / 1000
    secondsold = Math.floor(sectimeold);
    msPerDay = 24 * 60 * 60 * 1000
    msPerYear = 365 * 24 * 60 * 60 * 1000
    e_daysold = timeold / msPerDay
    e_yearsold = timeold / msPerYear
    daysold = Math.floor(e_daysold);
    yearsold = Math.floor(e_yearsold);
    //str = yearsold + "年";
    str += daysold + "天";
    str += d.getHours() + '时';
    str += d.getMinutes() + '分';
    str += d.getSeconds() + '秒';
    return str;
}
setInterval(function () {
    $('#run_time').html(runTime())
}, 1000);</script>

在<?php wp_footer();?>前适当的位置添加

网站在各种崩溃中运行了:<span id="run_time"></span>