為什么用let不顯示輸出結果,用var卻可以
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>無標題文檔</title>
</head>
<script type="text/javascript">
? var version = navigator.appVersion;
??
? document.write("平臺和版本信息:"+version+"<br />");
</script>
<body>
</body>
</html>
2022-07-23
let是局部變量,var是全局變量