Feature: #87033 - New TypoScript Property config.htmlTag.attributes

See forge#87033

Description

The new site handling functionality adds some attributes to the frontend rendering <html> tag automatically, even per language (e.g. "lang" and "dir" attributes) without having to use TypoScript anymore.

However, if custom properties should be added, e.g. <html lang="fr" amp>, this is not possible anymore without having to reintroduce TypoScript conditions or complex stdWrap functionality. In previous versions the property config.htmlTag_setParams was used to override all properties, but since there were conditions in place for languages, this was a one-liner change per language.

In order to use the full power of TypoScript flexibility, it is possible now to use config.htmlTag.attributes which allows to override and add custom attributes via TypoScript without having to re-add the existing attributes generated by SiteHandling.

This property supersedes the previous config.htmlTag_setParams option by providing a more flexible API to add attributes.

Examples:

config.htmlTag.attributes.class = no-js

Will result in <html lang="fr" class="no-js">.

It is even possible to add attributes without a value:

config.htmlTag.attributes.amp =

will render <html lang="it" amp>

Please note that "lang" attribute in these examples are auto-generated by Site configuration, depending on the value added there.

Impact

If the TypoScript option config.htmlTag.attributes is used, then config.htmlTag_setParams has no effect anymore.