<div class="container">
  <div class="slider">
    <img class="active" src="https://source.unsplash.com/gKk9rpyDryU">
    <img src="https://source.unsplash.com/VFGEhLznjPU">
    <img src="https://source.unsplash.com/InR-EhiO_js">
  </div>
  <nav class="slider-nav">
    <ul>
      <li class="arrow">
        <button class="previous">
          <span>
            <i class="ion-arrow-left-c"></i>
          </span>
        </button>
      </li>
      <li class="arrow">
        <button class="next">
          <span>
            <i class="ion-arrow-right-c"></i>
          </span>
        </button>
      </li>
    </ul>
  </nav>
</div>

$arrow: #3c376f;
$bg: #fef8f9;

* {
  box-sizing: border-box;
  &::before, &::after {
    box-sizing: border-box;
  }
}

body {
  margin: 0;
  background: $bg;
}

.container {
  max-width: 800px;
  margin: 0 auto;
  padding: 50px;
}

button {
  position: relative;
  display: inline-block;
  cursor: pointer;
  outline: none;
  border: 0;
  vertical-align: middle;
  text-decoration: none;
  background: transparent;
  padding: 20px 5px;
  color: $arrow;
  font-size: 2rem;
}

button span {
  position: relative;
  display: inline-block;
  transform: translateX(0);
  transition: transform 0.3s ease;
}

.previous:hover span {
  transform: translateX(-10px) scale(1.2);
}

.next:hover span {
  transform: translateX(10px) scale(1.2);
}

.slider-nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
}

.slider-nav li {
  display: flex;
  flex: 2;
  text-align: center;
}

img {
  max-width: 100%;
  display: none;
  box-shadow: 10px 10px 20px 0 rgba(94,47,59,0.2);
}

img.active {
  display: block;
  animation: fadeImg 0.8s;
}

.slider-nav .arrow {
  flex: 0 0 15%;
}

.slider-nav a {
  flex-basis: 100%;
  display: flex;
  align-items: center;
}

.slider-nav span {
  display: block;
  width: 100%;
}

@keyframes fadeImg {
  from {
    opacity: 0;
  }

  to {
    opacity: 1;
  }
}

const items = document.querySelectorAll('img');
const itemCount = items.length;
const nextItem = document.querySelector('.next');
const previousItem = document.querySelector('.previous');
let count = 0;

function showNextItem() {
  items[count].classList.remove('active');

  if(count < itemCount - 1) {
    count++;
  } else {
    count = 0;
  }

  items[count].classList.add('active');
  console.log(count);
}

function showPreviousItem() {
  items[count].classList.remove('active');

  if(count > 0) {
    count--;
  } else {
    count = itemCount - 1;
  }

  items[count].classList.add('active');
  console.log(count);
}

function keyPress(e) {
  e = e || window.event;
  
  if (e.keyCode == '37') {
    showPreviousItem();
  } else if (e.keyCode == '39') {
    showNextItem();
  }
}

nextItem.addEventListener('click', showNextItem);
previousItem.addEventListener('click', showPreviousItem);
document.addEventListener('keydown', keyPress);