<!DOCTYPE html>
<html lang="en">
<head>
<title>Opener</title>
<style>
body {
font-family: Arial, sans-serif;
font-size: 16px;
margin: 2em;
}
.grey {
color: #BDBDBD;
}
.green {
color: #43A047;
}
</style>
<script>
window.onload = function() {
if (window.opener) {
document.getElementById("opener").innerText = window.opener;
document.getElementById("opener").className = "green";
} else {
document.getElementById("opener").innerText = "Null";
}
if (window.name) {
document.getElementById("name").innerText = window.name;
document.getElementById("name").className = "green";
} else {
document.getElementById("name").innerText = "Empty String";
}
}
</script>
</head>
<body>
<h2>HTTP</h2>
 Referer: <?= $_SERVER["HTTP_REFERER"] ? '<span class="green">' . $_SERVER["HTTP_REFERER"] . '</span>' : '<span class="grey">None</span>' ?>
<h2>JavaScript</h2>
 window.opener: <span id="opener" class="grey">Enable JavaScript</span>
<br><br>
 window.name: <span id="name" class="grey">Enable JavaScript</span>
</body>
</html>