abstract：<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0">&
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<script type="text/javascript" >
var str = "hello world!"
//string類型的變量
document.write(str+'<br>');
document.write(typeof(str));
</script>
</head>
<body>
</body>
</html>
Correcting teacher：天蓬老師Correction time：2019-01-13 10:29:49
Teacher's summary：document.write(typeof(str));, 以后, 直接寫到控制臺(tái)查看吧: console.log(typeof(str));