var slideIndex = 1;

showSlides(slideIndex);



function plusSlide() {

    showSlides(slideIndex += 1);

}



function minusSlide() {

    showSlides(slideIndex -= 1);  

}



function currentSlide(n) {

    showSlides(slideIndex = n);

}



var interval_slides = setInterval(plusSlide,9000);



var tovar = 0;



function showSlides(element_id) {

   

    var element = document.getElementById('id');

    var slides = document.getElementsByClassName("item");

    var dots = document.getElementsByClassName("slider-dots_item");

    if (n > slides.length) {

      slideIndex = 1

    }

    if (n < 1) {

        slideIndex = slides.length

    }

    for (i = 0; i < slides.length; i++) {

        slides[i].style.display = "none";

    }

    for (i = 0; i < dots.length; i++) {

        dots[i].className = dots[i].className.replace(" active", "");

    }

    slides[slideIndex - 1].style.display = "block";

    dots[slideIndex - 1].className += " active";

}