```javascriptfunction show_date_time() {
window.setTimeout(show_date_time, 1000);
var BirthDay = new Date("2/02/2020");
var today = new Date();
var timeold = today.getTime() - BirthDay.getTime();
var sectimeold = timeold / 1000;
var secondsold = Math.floor(sectimeold);
var msPerDay = 24 * 60 * 60 * 1000;
var e_daysold = timeold / msPerDay;
var daysold = Math.floor(e_daysold);
e_hrsold = (daysold - e_daysold) * -24;
hrsold = Math.floor(e_hrsold);
e_minsold = (hrsold - e_hrsold) * -60;
minsold = Math.floor((hrsold - e_hrsold) * -60);
e_seconds = (minsold - e_minsold) * -60;
e_seconds = Math.floor((hrsold - e_hrsold) * -60);
e_seconds = Math.floor((minsold - e_minsold) * -60);
e_seconds = Math.floor(sectimeold % (24 * 3600));
e_seconds = Math.floor(e_seconds * (-1));
span_dt_dt.innerHTML = daysold + "天" + hrsold + "小时" + minsold + "分" + secondsold + "秒";
}
show_date_time();
```