<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    // typeof在检测null类型的时候会返回'object'类型
    // typeof在检测function类型的时候会返回'function'类型
    let a = 10;
    console.log(typeof a);
    let b =typeof a;
    console.log(typeof b)
</script>
</body>
</html>