This plugin is capable of extracting metadata from classes, random attributes, and child elements.
For example, you can do:
<li class="someclass {some: 'data'} anotherclass">...</li> OR <li data="{some:'random', json: 'data'}">...</li> OR <li><script type="data">{some:"json",data:true}</script> ...</li>
The default is the first method, but you can always change it by twiddling the options. This means that there is at least one option here that can appease you.
After that you can simply do:
var data = $('li.someclass').metadata(); if ( data.some && data.some == 'data' ) alert('It Worked!');
There’s also a bunch of options (like the ability to ignore braces {}).
For full documentation see http://docs.jquery.com/Plugins/Metadata.