<!DOCTYPE html>
<html>
<head>
<script src="/lib/jquery-1.12.2.min.js"></script>
<script>
$(document).ready(function(){
    $("p").add(document.getElementsByTagName("span")[0]).css("background-color", "yellow");
});
</script>

</head>
<body>

<p>A p element.</p>
<p>Another p element.</p>

<span>A span element.</span>
<span>A span element.</span><br><br>

<div>This example adds the same css style for the first span element (index 0), as the existing p elements.</div>

</body>
</html>