(function(){
    document.addEventListener('DOMContentLoaded', function() {
        var username = document.querySelector('input[type=text]'),
            password = document.querySelector('input[type=password]'),
            tombol = document.querySelector('input[type=submit]');

        tombol.addEventListener('click', function (e) {
            e.preventDefault();
            if(username_exist(username.value)){
                if(password_exist(password.value, username.value)){
                    alert("SELAMAT ANDA BERHASIL MASUK");
                }else{
                    alert("Password salah blokkkk");
                }
            }else{
                alert("Username salah pooottt");
            }
        })


    });

    var database = [
        { uname: "paijo", password: "123" },
        { uname: "kontol", password: "123" },
        { uname: "jembot", password: "123" }
    ];

    function username_exist(uname){
        if(database.find(function(data){ return data.uname == uname })){
            return true;
        }else{
            return false;
        }
    }
    function password_exist(password, uname){
        if(database.find(function(data){ return data.password == password && data.uname == uname })){
            return true;
        }else{
            return false;
        }
    }
})()