I'm not sure your question makes a lot of sense (I'm sorry). UX is platform independant; you can design the UX of a chair, of a TV remote, for a POS terminal, as well as for a website. Even with website design, there are dozens of technologies that can be used to build the interaction of the site.
You need to be familiar with the capabilities of the technology you are using. That's it. The more familiar you are with your technology (whatever it may be), the better you will be able to design your interface around the trade-offs inherent to your platform.
You can't 'quantify' this kind of knowledge into some arbitrary percentage. You need to understand the technical limitations in order to be a good designer. The more knowledgeable about the capabilities of your technology you are, the better a designer you will be. But whether that technology is jQuery, Java, or plastic injection molding (for designing a TV remote) really is not relevant.