I am trying to build a simple static website. I have a list of 3 different categories which are in 3 div elements. I want to filter the list with menu items using javascript and hide other items of the list.

HTML

<div class="sorting">
  <ul class="sorting list-inline">
    <li>
      <a href="#" class="active" data-group="all">All</a>
    </li>
    <li>
      <a href="#" class="" data-group="category1">category 1</a>
    </li>
    <li>
      <a href="#" class="" data-group="category2">category 2</a>
    </li>
    <li>
      <a href="#" class="" data-group="category3">category 3</a>
    </li>
  </ul>
</div>
<div class="list" data-groups="["category1"]">
  <ul>
    <li>
      category 1
    </li>
    <li>
      category 1
    </li>
    <li>
      category 1
    </li>
  </ul>
</div>
<div class="list" data-groups="["category2"]">
  <ul>
    <li>
      category 2
    </li>
  </ul>
</div>
<div class="list" data-groups="["category3"]">
  <ul>
    <li>
      category 3
    </li>
    <li>
      category 3
    </li>
  </ul>
</div>

CSS

.sorting {
  margin: 0;
  border-top: 1px solid #f6f6f6;
  border-right: 1px solid #f6f6f6;
  border-bottom: 2px solid crimson;
  height: 47px;
  margin-bottom: 60px;
}

.sorting li {
  padding: 0;
  float: left;
  list-style: none;
}

.sorting li a {
  position: relative;
  display: inline-block;
  padding: 0 30px;
  line-height: 44px;
  height: 44px;
  border-left: 1px solid #f6f6f6;
  border-right: 1px solid #f6f6f6;
  text-transform: uppercase;
  text-decoration: none;
  font-family: "Ubuntu", sans-serif;
  color: crimson;
  font-size: 17px;
  font-weight: 300;
}

.sorting li a:hover,
.sorting li a.active {
  background-color: crimson;
  color: #ffffff;
  border-color: crimson;
}

.sorting li a:hover:after,
.sorting li a.active:after {
  border-color: crimson;
}

.sorting li a:after,
.sorting li a.acitve:after {
  content: "";
  position: absolute;
  top: -1px;
  left: -1px;
  right: -1px;
  display: block;
  border-top: 1px solid #dddddd;
  -webkit-transition: all 0.25s ease-in-out;
  -o-transition: all 0.25s ease-in-out;
  -moz-transition: all 0.25s ease-in-out;
  transition: all 0.25s ease-in-out;
}

.sorting li a.active:before {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: -11px;
  margin: 0 auto;
  width: 0;
  height: 0;
  border-style: solid;
  border-width: 10px 10px 0 10px;
  border-color: crimson transparent transparent transparent;
  z-index: 99;
}

.sorting li+li a {
  border-left: 0;
}

.sorting li+li a:after,
.sorting li+li a.active:after {
  left: 0px;
}

.list ul li {
  list-style: none;
  font-family: "Poppins", sans-serif;
  margin-bottom: 23px;
  text-align: justify;
  font-size: 18px;
  font-weight: 500;
}

.list ul li span {
  color: crimson;
}

.list ul li a {
  background: crimson;
  color: #fff;
  font-size: 14px;
  font-weight: 500;
  margin-left: 7px;
  padding: 0 4px;
  border-radius: 20px;
  border: 2px solid crimson;
  transition: all 0.3s ease;
}

.list ul li a:hover {
  color: crimson;
  background: none;
}

Kindly help me to sort it out. I am having difficulty understanding java functions.
Thank you very much.