代码示例：（标识：eg_js_timing_settimeout_clock）
<!DOCTYPE html>
<html>
<head>
<script>
function startTime() {
var today = new Date();
var h = today.getHours();
var m = today.getMinutes();
var s = today.getSeconds();
m = checkTime(m);
s = checkTime(s);
document.getElementById('txt').innerHTML =
h + ":" + m + ":" + s;
var t = setTimeout(startTime, 500);
}
function checkTime(i) {
if (i < 10) {i = "0" + i}; // 在数字 < 10 之前加零
return i;
}
</script>
</head>
<body onload="startTime()">
<div id="txt"></div>
</body>
</html>
