jQuery忽略响应

<script type="text/javascript">
    function SubmitForm(method) {
        var login = document.form.login.value;
        var password = document.form.password.value;
        $.post("backend.php", { 
            login: login, 
            password: password, 
            method: method},
            function(data){
            alert(data.message); 
            console.log(data.refresh); 
        }, "json");
    }
</script>

backend{"message":"Log in credentials are not correct","refresh":"false"}