CSSとJavaScriptでタブを作成するにはどうすればよいですか？

CSSとJavaScriptを使用してタブを作成するためのコードは、次のとおりです-

例

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>>
.tab {
   overflow: hidden;
   border: 2px solid gray;
   background-color: #FFE4C4;
}
.tab button {
   background-color: inherit;
   float: left;
   cursor: pointer;
   padding: 14px 16px;
   font-size: 15px;
}
.tab button:hover {
   background-color: gray;
}
.tab button.active {
   background-color: #ccc;
}
.demo2 {
   display: none;
   padding: 3px 12px;
}
</style>
</head>
<body>
<h2>Examination</h2>
<p>Following is the exam information:</p>
<div class="tab">
<button class="demo" onclick="infofunc(event, 'dates')">Exam Dates</button>
<button class="demo" onclick="infofunc(event, 'centre')">Exam Centre</button>
</div>
<div id="dates" class="demo2">
<h3>Dates</h3>
<p>Exam date will be announced on 25th March.</p>
</div>
<div id="centre" class="demo2">
<h3>Centre</h3>
<p>Exam Centre will be announced on 30th March.</p>
</div>
<script>
function infofunc(e, info) {
   var i, content, links;
   content = document.getElementsByClassName("demo2");
   for (i = 0; i < content.length; i++) {
      content[i].style.display = "none";
   }
   links = document.getElementsByClassName("demo");
   for (i = 0; i < links.length; i++) {
      links[i].className = links[i].className.replace(" active", "");
   }
   document.getElementById(info).style.display = "block";
   e.currentTarget.className += " active";
}
</script>
</body>
</html>