This is news to me. From what I can find (which is not much), it seems like XHTML5 is a further constraint on HTML5. So legal XHTML5 is legal HTML5. https://

This is news to me. From what I can find (which is not much), it seems like XHTML5 is a further constraint on HTML5. So legal XHTML5 is legal HTML5. https://en.wikipedia.org/wiki/HTML5#XHTML_5_(XML-serialized_HTML_5) https://en.wikipedia.org/wiki/HTML5#XHTML_5_(XML-serialized_... If that's true, that means <div /> is not valid XHTML5 because 1) trailing slashes don't close tags in html and 2) div elements require a closing tag. And if that's true, then it's still different from JSX. But this XHTML5 thing might be surpassing my comprehension.