htmlClass pattern validation is too restrictive

[thomas-kl1]

Resource: https://www.w3.org/TR/CSS22/syndata.html
Part 4.1.3

In CSS, identifiers (including element names, classes, and IDs in selectors) can contain only the characters [a-zA-Z0-9] and ISO 10646 characters U+0080 and higher, plus the hyphen (-) and the underscore (_); they cannot start with a digit, two hyphens, or a hyphen followed by a digit. Identifiers can also contain escaped characters and any ISO 10646 character as a numeric code (see next item). For instance, the identifier "B&W?" may be written as "B&W?" or "B\26 W\3F".

Preconditions (*)

1. Add a new container in your layout
2. Add a htmlClass with a character like "@"

Steps to reproduce (*)

1. Add a new container in your layout
2. Add a htmlClass with a character like "@"

Expected result (*)

1. The container is added to the dom with the correct class attribute value

Actual result (*)

1. Layout validation fails because it says the character is not allowed

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[thomas-kl1]

@magento I am working on this

[ihor-sviziev]

Hi @thomas-kl1,
Could you describe what is the use case of using the @ symbol in the class names? Magento definitely not supporting, but I don't think there is some valid use case for using such things.

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[thomas-kl1]

@ihor-sviziev there is many css framework that use "@ " in classnames. Anyway the current validation it too much restrictive regarding this ressource https://www.w3.org/TR/CSS22/syndata.html

There is no valid point to prevent using other characters and some could be easily escaped thanks to the escaper object.
Many projects I work on, have to use patches to override this rule or to use alternative blocks and templates, which is redundant and could be avoided

[ihor-sviziev]

TBH I never saw that "at" symbol used in the class names, I also didn't see it in any CSS frameworks, and I personally don't think it's a good idea because it will confuse people. Maybe you could provide some examples?

I still believe this issue having a too-small amount of people. Probably priority for this issue should be P4, which is the lowest priority.

[thomas-kl1]

You missed the point. The point: https://www.w3.org/TR/CSS21/syndata.html#value-def-identifier

If you need the full standard documentation, there's the links:

• https://www.w3.org/TR/CSS/#css
• https://www.w3.org/TR/css-syntax-3/#syntax-description
• https://www.w3.org/TR/css-syntax-3/#style-rule
• https://www.w3.org/TR/css-syntax-3/#parsing
• https://www.w3.org/TR/selectors-4/#class-html
• https://www.w3.org/TR/selectors-4/#id-selector

I never saw that "at" symbol used in the class names, I also didn't see it in any CSS frameworks

That's your thought, it doesn't make it true. Some in-house and proprietary frameworks could use chars that are not part of the current rules:

• [a-zA-Z][a-zA-Z\d\-_:]*
• [a-zA-Z][a-zA-Z\d\-_]*(\s[a-zA-Z][a-zA-Z\d\-_]*)*

I personally don't think it's a good idea because it will confuse people

That's also your opinion, developers are free to use it or not, so there is no confusion either.

I don't think there is some valid use case for using such things

Since some major companies are using it, it's pretty much valid to me, so it's still opinionated to me

What's the reason behind those Magento's rules? What is the legitimate design to write these regex patterns?
A framework should be a friendly tool for developers to help them to quickly solves common problems. Here it adds a constraint without any reasons.

Also I've used the "@" character as an example, but it could be any that follows the standard:

In CSS, identifiers (including element names, classes, and IDs in selectors) can contain only the characters [a-zA-Z0-9] and ISO 10646 characters U+00A0 and higher, plus the hyphen (-) and the underscore (_); they cannot start with a digit, two hyphens, or a hyphen followed by a digit. Identifiers can also contain escaped characters and any ISO 10646 character as a numeric code (see next item). For instance, the identifier "B&W?" may be written as "B&W?" or "B\26 W\3F".

We could agree or disagree to use such characters for identifiers, but we might follow the standards. The decision to use such characters is scoped to project, not to the framework.