Require a specific case for DOCTYPE (doctype-style)

While DOCTYPE is case-insensitive in the standard this rule requires it to be a specific style. The standard consistently uses uppercase which is the default style for this rule.

Mixed case it not supported.

Rule details

Examples of incorrect code for this rule:

<!Doctype html>
error: DOCTYPE should be uppercase (doctype-style) at inline:1:1:
> 1 | <!Doctype html>
    | ^^^^^^^^^^

1 error found.

Examples of correct code for this rule:

<!DOCTYPE html>


This rule takes an optional object:

    "style": "uppercase",