Fallback from CDN to origin if CDN is blocked by firewall

kickcdn.php

<?php
/*
 * Plugin Name: Kick CDN
 * Description: Kicks the CDN if it's unavailable
 * Author: Benjamin J. Balter
 * Version: 1.0
 */
 
add_action( 'wp_head', 'bb_kick_cdn', 100 );

function bb_kick_cdn() { ?>
<script>window.onload=function(){if("undefined"==typeof jQuery){var a=document.createElement("script");a.type="text/javascript";a.onload=a.onreadystatechange=kickCDN;a.src="//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js";document.body.appendChild(a)}};function kickCDN(){jQuery(document).ready(function(a){a.each(["src","href"],function(d,b){a("["+b+'^="http://cdn.benbalter.com"]').each(function(d,c){a(c).attr(b,a(c).attr(b).replace("http://cdn.benbalter.com","http://ben.balter.com"))})})})};</script>
<?php }

/*
Unminified:

window.onload = function () {
    if (typeof jQuery == 'undefined') {
		var jQ = document.createElement('script');
		jQ.type = 'text/javascript';
		jQ.onload = jQ.onreadystatechange = kickCDN;
		jQ.src = '//ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js';
		document.body.appendChild(jQ);
    } 
};

function kickCDN() { 		
	jQuery(document).ready( function( $ ) { 
		var from = 'http://cdn.benbalter.com';
		var to = 'http://ben.balter.com';
		$.each( [ 'src', 'href'], function( k, attr ) {
			$('[' + attr + '^="' + from + '"]').each( function( k, elem ) { 
				$(elem).attr( attr, $(elem).attr(attr).replace( from, to ) ); } );	
		} );
	});
}

*/