<head>
    <h1>Login and password</h1>
</head>

<body>
    <script>
        let rightLogin = "admin";
        let rigthtPass = "qwerty";
        let login = prompt("Enter login");
        let valid = login === rightLogin;
        if (valid) {
            let pass = prompt("Enter password");
            valid = pass === rigthtPass;
        }
        if (valid)
            alert("Congrats!!");
        else
            alert("wrong credentials!!! SUKA");
    </script>
</body>