New Rule: function-no-unknown

[SwetaTanwar]

Rule details

Disallow unknown functions.

What type of rule is this?

Warns about a potential problem

Example code

The following patterns are considered problems:


a { transform: unknown(1); }


The following patterns are not considered problems:


a { transform: scale(1); }



a { transform: --custom-function(1); }

Participation

• I am willing to submit a pull request to implement this rule.

Additional comments

Prior Art: https://stylelint.io/user-guide/rules/function-no-unknown/

[nzakas]

I assume this is inspired by the Stylelint rule? (Please be sure to mention prior art when suggesting a new rule.)

I'm not 100% sure, but I think no-invalid-properties might catch unknown functions. Can you double-check?

[thecalamiity]

I'm not 100% sure, but I think no-invalid-properties might catch unknown functions. Can you double-check?

It does.

[nzakas]

Thanks for verifying @thecalamiity. Closing as this case is already covered.

As a note: Stylelint tends to have very narrowly focused rules whereas ESLint tends to have broader scope of rules. When we consider porting something from Stylelint it's helpful to double-check that we don't already have a rule that covers the same case.