custom filter for jquery

gistfile1.txt

$.expr[':'].external = function(elem,index,match) {
    var url = elem.href || elem.src,
        loc = window.location;
    return !!url.match(new RegExp('^' + loc.protocol + '//' + '(?!' + loc.hostname + ')' ));
};


// You can now use it within your selectors:
 
// Find all external anchors:
$('a:external');
 
// Find all external script elements:
$('script:external');
 
// Determine if link is external:
$('a#mylink').is(':external'); // true or false

[external link]: http://james.padolsey.com/javascript/extending-jquerys-selector-capabilities/