document.getElementById("slider-left").onclick = sliderLeft;
autoSlider ();
let left = 0;
let timer;
function autoSlider () {
timer = setTimeout (sliderLeft, 1000);
}
function sliderLeft() {
let polosa = document.getElementById('polosa');
left = left-128;
if (left < -256) {
left = 0;
}
polosa.style.left = left +"px";
}