<script>

        $(document).ready(function(){
            $('form').on('submit',function(){
            $.ajax({
                    type:'post',
                    url:'<?php echo base_url(); ?>users_controller/login_check',
                    data: {
                        username:'username',
                        password:'password'
                    }
                    success:function(detail)
                    {
                        if(detail !== 'error')
                        {
                            window.location.href=detail;
                        }
                        else
                        {
                        $('.error').html('');
                        $('.error').html('<p class="alert alert-danger">Invalid username or password</p>');
                        $('.error').show();
                        }
                    }
                });
                return false;
            });
        });

</script>