Self-closing tags do not exist in HTML, warn/error when using them

[KieranP]

In the docs (https://herb-tools.dev/specification/html), it refers to <img /> and <div /> as self-closing tags. Except in HTML5 (the current standard), there is no such thing. It's a carry-over from the XHTML days, and it doesn't work as people expect.

Browsers interpret <div />Hello as <div>Hello</div>, <script />Hello as <script>Hello</script>, etc, leading to a lot of issues. More on that here: https://developer.mozilla.org/en-US/docs/Glossary/Void_element#self-closing_tags

So I highly recommend that Herb throw warnings (maybe even errors) and link to the above developer docs when any "self-closing" tags are encountered. This would help the Rails community write more compliant HTML code.

[marcoroth]

Yeah I agree! This is a good idea. Thanks for opening this issue @KieranP!

I still haven't figured out 100% where this logic should go. Like, should this be as part of the parser directly or should this should be a lint-rule in the linter itself.

I guess what we could do for now, until we have the linter, is to add this logic to the parser itself, and then later once we have the linter, move the rule over.