为什么下面代码在本课程里能看到效果，在vscode里选择浏览器打开看不到？
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>屏幕分辨率的高和宽</title>
</head>
<body>
<script type="text/javascript">
var s ="网页可见区域宽："+ document.body.clientWidth;
s+="\r\n网页可见区域高："+ document.body.clientHeight;
s += "\r\n网页正文全文宽："+ document.body.scrollWidth;
s += "\r\n网页正文全文高："+ document.body.scrollHeight;
s += "\r\n网页正文部分上："+ window.screenTop;
s += "\r\n网页正文部分左："+ window.screenLeft;
s += "\r\n屏幕分辨率的高："+ window.screen.height;
s += "\r\n屏幕分辨率的宽："+ window.screen.width;
s +="\r\n屏幕可用工作区高度："+ window.screen.availHeight;
s +="\r\n屏幕可用工作区宽度："+ window.screen.availWidth;
alert(s);
document.write(s) ;
</script>
</body>
</html>
