Testing HTML/CSS/Javascript skills when hiring [closed]

Question

When hiring a front-end developer, what specific skills and practices should you test for? What is a good metric for evaluating their skill in HTML, CSS and Javascript?

Obviously, table-less semantic HTML and pure CSS layout are probably the key skills. But what about specific techniques? Should he/she be able to effortlessly mock up a multi-column layout? CSS sprites? Equal height (or faux) columns? Does HTML tag choice matter (ie, relying too heavily on <div>)? Should they be able to explain (in words) how floats work?

And what about javascript skills? How important is framework experience (jQuery, Prototype, etc). today?

Obviously, the details of the position and the sites they'll be working on are the best indication of what skills are needed. But I'm wondering what specific skills people might consider to be deal-breakers (or makers) when creating tests for candidates.

Answer 1

When I interview people for a position of Client-Side developer I try to figure out:

 1) Understanding DOM (what is that, how is it related to HTML etc) 2) Understanding XML/namespaces 3) Understanding JavaScript (object-oriented? what otherwise) 4) Knowing approaches to componentization (XBL, HTC) - plus 5) Understanding OO principles 6) JavaScript closures 7) Memory leaks in browsers 

The only simple test case I give right away:

 <script type="text/javascript"> var a = 1; </script> 

I suggest interviewee to explain in technical terms that line.

And I also check on overall awareness of the current state of the Web technologies, among other questions I suggest designing a web-browser where interviewee is suggested to pick technologies he would put into his brand-new creature, suggest ones that might be missing from the current client-side platform.