I have about 20 years of experience with programming, most of that on the job, and right now, I define myself as a Web Developer, because I think about half my expertise lies in the all too extended "web" field, both server side and client side, and because in the last years I'm mostly doing web development.
I know my javascript, jQuery, jQueryUI, HTML4-5, css2-3 and some frameworks like backbone.js and angularJS
Since university I've always been interested in Man-Machine Interaction, UI and UX.
Recently, I saw the label "Web UI Developer" tossed around, and I thought that would be something I would like to qualify for. And I'd really like to qualify with confidence. I didn't find any certificate or similar, and I don't think there are any.
Is the only way to qualify as a Web UI Developer having a job as one?
What are the skills I need to have, and the resources I can use to acquire them?