<!DOCTYPE html>
<html>
<body>
<p>点击这个按钮，获得基于时间的问候。</p>
<button onclick="myFunction()">点击这里</button>
<p id="demo"></p>
<script>
function myFunction()
{
var x="";
var time=new Date().getHours();
if (time<20)
x="Good day";
}
else
x="Good evening";
document.getElementById("demo").innerHTML=x;
</script>
</body>
</html>