Selecting an element in iFrame jQuery

var iframe = $('iframe'); // or some other selector to get the iframe
$('[tokenid=' + token + ']', iframe.contents()).addClass('border');

Also note that if the src of this iframe is pointing to a different domain, due to security reasons, you will not be able to access the contents of this iframe in javascript.

Take a look at this post: http://praveenbattula.blogspot.com/2009/09/access-iframe-content-using-jquery.html

$("#iframeID").contents().find("[tokenid=" + token + "]").html();

Place your selector in the find method.

This may not be possible however if the iframe is not coming from your server. Other posts talk about permission denied errors.

jQuery/JavaScript: accessing contents of an iframe

when your document is ready that doesn't mean that your iframe is ready too,
so you should listen to the iframe load event then access your contents:

$(function() {
    $("#my-iframe").bind("load",function(){
        $(this).contents().find("[tokenid=" + token + "]").html();
    });
});