HTML comments are not considered comments

In JavaScript, HTML comments are a valid replacement for single line comments.
They are considered comments in Node.js, inline script tags, external js file, etc.

<!-- No comment.
// Comment.

Even GitHub doesn't seem to understand this syntax 🤔

Your grammar does not seem to support them, and mistakes them as a syntax error.

Link to the relevant part of the spec

In the spec this syntax appears under additional syntax for web browsers, yet you do support the other additional syntax in that section, such as legacy octal numeric literals and octal string escapes, but not HTML comments.

まず、JavaScript コメント用の TypeScript TextMate 文法規則を見つけ、issue でリンクされている ECMAScript の HTML に似たコメントのセクションと比較します。示されている HTML コメントの例に対して文法を検証し、構文エラーとして報告されなくなったことを確認します。