Do custom elements require closing tags?

Question

The elements I defined (which don't require content) seem to work just fine without the closing tag. I'm wondering if this is just a quirk of the browser.

What is the verdict? Is it theoretically possible? What if the parser sees the element before it is defined?

Answer 1

Yes. Custom elements require closing tags. Due to parser reasons, only certain tags in HTML are allowed to self-close.

and:

http://www.w3.org/TR/ html-markup/syntax.html#syntax-elements