root selector
Description: Selects the element that is the root of the document.
version added: 1.9jQuery( ":root" )
In HTML, the root of the document, and thus the element that $(":root") selects, is always the <html> element.
Example:
Display the tag name of the root element.
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>root demo</title>
<style>
span.fot {
color: red;
font-size: 120%;
font-style: italic;
}
</style>
<script src="https://code.jquery.com/jquery-1.10.2.js"></script>
</head>
<body>
<div id="log">The root of this document is: </div>
<script>
$( "<b></b>" ).html( $( ":root" )[ 0 ].nodeName ).appendTo( "#log" );
</script>
</body>
</html>