<div class="home__block" id="home__block"></div>
<div class="works__block" id="works__block"></div>
<div class="about__block" id="about__block"></div>
<div class="contact__block" id="contact__block"></div>
<div class="hire__block" id="hire__block"></div>
<nav class="i__side__nav">
<div class="side__nav__line"></div>
<ul class="side__nav" id="side__nav">
<li class="home__item" id="item1">Home</li>
<li class="works__item" id="item2">Works</li>
<li class="about__item" id="item3">About</li>
<li class="contact__item" id="item4">Contact</li>
<li class="hire__item" id="item5">Hire us</li>
</ul>
</nav>
.block {
display: none;
}
.block.active {
display: block;
}
document.querySelector('.side__nav').addEventListener('click', e => {
const item = e.target.closest('.item');
if (item) {
const index = [...e.currentTarget.children].indexOf(item);
document.querySelectorAll('.block').forEach((n, i) => n.classList.toggle('active', i === index));
}
});