const prevButton = document.querySelector('#gallery .buttons .prev');
const nextButton = document.querySelector('#gallery .buttons .next');
const images = document.querySelectorAll('#gallery .photos img');
let i = 0;
prevButton.onclick = function () {
images[i].className = '';
i -= 1;
if (i < 0) {
i = images.length - 1;
}
images[i].className = 'showed';
}
nextButton.onclick = function () {
images[i].className = '';
i += 1;
if (i >= images.length) {
i = 0;
}
images[i].className = 'showed';
}