<!DOCTYPE html>
<html lang="en-US">
<head>
<style>
a{
display:block;
margin-bottom:10px;
font-size:18px;
text-decoration:none;
color:green;
}
a:nth-child(4){
color:red;
}
</style>
</head>
<body>
<p>Random Number is : <output id="rand-output"></output></p>
<p>Click on the following links one by one to see how <strong>rel = "noopener"</strong> works.</p>
<!-- with rel="noopener"-->
<a rel="noopener" href="/test/test-file" target="_blank"><a target="_blank" rel="noopener"></a>
<!-- without rel="noopener"-->
<a href="/test/test-file" target="_blank"><a target="_blank"></a>
<script>
var x = document.getElementById("rand-output");
setInterval(function(){
x.innerHTML=Math.random();
}, 50);
</script>
</body>
</html>