Rule Proposal: comment-capitalizing

From requireCapitalizedComments and disallowCapitalizedComments.

This rule will enforce which the first character is an upper case or a lower case.

{
    "comment-capitalizing": ["error", "always" or "never"],
    // or
    "comment-capitalizing": [
        "error",
        {
            "capitalize": "always" or "never",
            "markers": ["*"],
            "ignorePattern": "^\s*(?:eslint|jshint|jslint|istanbul|global|exported|jscs|falls?\s?through)",
            "ignoreInlineComments": false,
            "overrides": {
                "block": null,  // e.g. "always", {capitalize: "always", markers: ["!"]}, ...
                "line": null
            }
        }
    ]
}

• "always" (default) - Requires the first alphabetical character of a comment to be uppercase, unless it is part of a multi-line textblock.
• "never" - Requires the first alphabetical character of a comment to be lowercase.
• markers (default is ["*"]) - If the head of comments matched to markers, this rule cut the matched part off, then checks the comment capitalizing. (this is similar to the markers option of spaced-comment rule)
• ignorePattern (default is "^\s*(?:eslint|jshint|jslint|istanbul|global|exported|jscs|falls?\s?through)") - If the comment content (except the part that markers option has matched) matches the given regexp pattern, this rule ignore the comment.
• ignoreInlineComments (default is false) - If this is true, this rule will be applied to only comments which are at the head of each line. (from requireCapitalizedComments’s inlined option)
• overrides - People can override setting for each line or block comment.

[platinumazure]

@eslint/eslint-tsc I don’t know if we still want to expedited-accept JSCS compat issues or if we should go through the usual new rule process. I have a couple of open questions about non-ASCII and non-letter characters, but this otherwise seems like an actionable proposal and I think this should be accepted.

If we are not expediting JSCS compat issues, I will champion this rule.

[platinumazure]

@nzakas I’d like to propose a modification to @mysticatea’s proposal in that case:

• onlyHeader option to be renamed to ignoreInlineComments, with the values still being boolean, default false, and having the same meaning as the proposal.