js自动时间

function showTime() {
	//时间
		nowtime = new Date();
		year = nowtime.getFullYear();
		month = nowtime.getMonth() + 1;
		date = nowtime.getDate();
		document.getElementById("mytime").innerHTML = year + "年" + month + "月" + date + "日" + nowtime.toLocaleTimeString();

	}
	setInterval("showTime()", 1000);

　　

<span id="mytime">__年_月_日</span>