HTML5 <meta charset="utf-8">

[lerni]

Description

<meta charset="utf-8"> should be used exclusively, instead of <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> or both as it is not needed for HTML5. W3C Validator also flags self-closing tags as an issue. While Symfony has reverted such a change, still it would make sense to remove those esp. in light of PHP 8.4 DOM HTML5 parsing. What is your opinion on handling self-closing tags?

Manual testing steps

A PR will follow in the CMS for ensuring HTML5 compliance. Additionally, simple theme should be updated to address this issue. Ultimately, only a single<meta charset="utf-8"> should be used.

Issues

#7438

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[GuySartorelli]

<meta charset="utf-8"> should be used exclusively, instead of <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> or both as it is not needed for HTML5.

Is there some docs or an RFC or something along those lines you could link me to for this?

What is your opinion on handling self-closing tags?

If there is clear, specific advice from an appropriately authoritative source, then we should follow that advice. In the absence of specific advice I'd be inclined to leave them how they are.

[lerni]

I think the links in #3031 should describe why to use <meta charset="utf-8"> instead of <meta http-equiv="Content-Type" content="text/html; charset=utf-8">.

Essentially, it's the way HTML5 is written those days. The longer version is a legacy from HTML4. The shorter version is recommended by the HTML5 specification, is easier to read and more concise. It's equally well supported and achieves the same result as the longer version.

As linked in #3031 W3C recommends not using trailing slashes on void elements. This is because it has no effect and interacts badly with unquoted attribute values.

1. MDN Web Docs

   • Void Elements documentation
   • Recommends against using self-closing syntax in HTML5

2. HTML Living Standard (WHATWG)

   • Void elements section
   • States void elements must not have end tags

3. W3C HTML5 Specification

   • Section 13.1.2: Elements
   • Mentions that trailing slashes on void elements are optional and have no effect

The consensus across these sources is that trailing slashes on void elements:

• Are unnecessary in HTML5
• Add no semantic value
• May cause issues with unquoted attributes
• Should be omitted for cleaner, more consistent code

However, it's worth noting that DOMDocument versions before PHP 8.4 may not support void elements without trailing slashes, as linked above. I have no clear view on it, but sooner or later Silverstripe should follow the latest recommendations.