function validatePassword(){
            var password = document.getElementById("password");
            var confirm_password = document.getElementById("confirm_password");

            password.onchange = validatePassword;
            confirm_password.onkeyup = validatePassword;

            if(password.value != confirm_password.value) {
                alert("pw is wrong");
                confirm_password.setCustomValidity("Passwords Don't Match");
            } else {
                confirm_password.setCustomValidity('');
            }
        }