字面量(JS)

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>字面量</title>
    <script>.log(18);
        console.log('18');
        console.log(true);
        console.log(undefined);
        console.log(null);</script>
</head>

<body>

</body>

</html>