<!DOCTYPE html>
<html>
<body>
<h2>JavaScript setSeconds()</h2>
<p>setSeconds() 方法设置日期对象的秒数（0-59）：</p>
<p id="demo"></p>
<script>
var d = new Date();
d.setSeconds(30);
document.getElementById("demo").innerHTML = d;
</script>
</body>
</html>