app.post('/loginol', function(req, res, next) {
    passport.authenticate('local-login', function(error, user, info) {
        if(error) {
            return res.status(500).json(error);
        }
        if(!user) {
            console.log("user bulunamadi");
            return res.json("bulunamadi");
        }
        var data=[];
        data.push(user);

        res.json(data);
        console.log("user"+user);

    })(req, res, next);
});

<script type="text/javascript">
        $(document).ready(function(){
            $("#loginol").click(function(){
                console.log("loginol");

                var username = $("#username").val();
                var password = $("#password1").val();
                console.log("username"+username);
                console.log("password"+password);
                data={};
                data.username=username;
                data.password=password;
                $.ajax({
                    type: "POST",
                    url: '/loginol',
                    data:  data,
                    success: function(data) {
                        if(data !="bulunamadi"){

                            document.getElementById("loginkismi").style.visibility = "hidden";
                            $("#kullanicikismi").append("<li>"+data+"</li>")
                            document.getElementById("kullanicikismi").style.visibility = "visible";
                        }
                    }
                });
            });
        });
    </script>