Без всякого javascript все может работать.
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<style type="text/css">
* {
list-style: none;
text-decoration: none;
margin: 0;
padding: 0;
}
ul {
background: #afafaf;
display: inline-block;
width: 420px;
border-right: 1px solid #000;
}
ul li {
padding: 6px 0;
background: #fff;
display: inline-flex;
align-items: center;
justify-content: space-between;
}
ul li:hover {
background: lightgreen;
}
ul li a {
color: #000;
}
ul li:hover a,
ul li:hover .fa {
color: #fff;
}
ul li .fa {
display: inline-block;
width: 30px;
height: 30px;
display: inline-flex;
align-items: center;
justify-content: center;
}
.leftside {
margin-left: 16px;
display: inline-block;
width: 30px;
height: 30px;
display: inline-flex;
}
.rightside {
margin-right: 16px;
visibility: hidden;
width: 30px;
height: 30px;
display: inline-flex;
}
.centerplace {
width: 328px;
display: inline-flex;
align-items: center;
justify-content: space-between;
}
.nestedblock{
display: inline-flex;
align-items: center;
justify-content: center;
margin:0 auto;
}
/* Добавил это */
ul:not(:hover) .centerplace,
ul:not(:hover) .rightside
{
display: none;
}
</style>
</head>
<body>
<ul id="sidemenu">
<li>
<div class="leftside">
<i class="fa fa-home"></i>
</div>
<div class="centerplace">
<a href="" class="nestedblock">Техника для кухни</a>
</div>
<div class="rightside">
<i class="fa fa-home"></i>
</div>
</li>
<li>
<div class="leftside">
<i class="fa fa-home"></i>
</div>
<div class="centerplace">
<a href="" class="nestedblock">Бытовая техника для дома</a>
</div>
<div class="rightside">
<i class="fa fa-home"></i>
</div>
</li>
<li>
<div class="leftside">
<i class="fa fa-home"></i>
</div>
<div class="centerplace">
<a href="" class="nestedblock">Ноутбуки и компьютеры</a>
</div>
<div class="rightside">
<i class="fa fa-home"></i>
</div>
</li>
<li>
<div class="leftside">
<i class="fa fa-home"></i>
</div>
<div class="centerplace">
<a href="" class="nestedblock">Комплектующие</a>
</div>
<div class="rightside">
<i class="fa fa-home"></i>
</div>
</li>
</li>
</ul>
</body>
</html>