src/manipulation/var/rtagName.js

define( function() {
	"use strict";

	// rtagName captures the name from the first start tag in a string of HTML
	// https://html.spec.whatwg.org/multipage/syntax.html#tag-open-state
	// https://html.spec.whatwg.org/multipage/syntax.html#tag-name-state
	return ( /<([a-z][^\/\0>\x20\t\r\n\f]*)/i );
} );