<!DOCTYPE html>
<html>
<body>
<h2>我的标题</h2>
<p>更新代码并单击“运行代码”按钮查看结果。</p>
<p id="demo"></p>
<script>
var x = 5;
var y = 6;
var z = x + y;
document.getElementById("demo").innerHTML =
"z 的值为：" + z;
</script>
</body>
</html>