fix: Make www case-sensitive when detecting link starts

[vaskkey]

Marked version: 16.3.0

Markdown flavor: GitHub Flavored Markdown

Description

• Fixes issue with case-insensitive URL detection for www. prefix
• Adds support for case-insensitive http and ftp prefixes in text

Expectation

Only lowercase www. should be detected as the start of an autolink. Variants like Www.example.com or WWW.example.com should be treated as plain text, not converted to links.

Case insensitive http or ftp like HtTp"// that is in text e.g. test HTTP://example.com should be autolinked

Result

Previously, the URL regex pattern used the i flag (case-insensitive), causing www., Www., WWW., and other case variations to be detected as autolink starts. This was inconsistent with how GitHub handles autolinks.

What was attempted

Modified the inlineGfm.url regex in src/rules.ts to:

• Remove the case-insensitive flag ('i')
• Make protocol detection case-insensitive by replacing the protocol pattern with [fF][tT][pP]|[hH][tT][tT][pP][sS]?
• Keep www. case-sensitive (lowercase only)

Added test cases to verify:

• www.example.com - converted to link
• Www.example.com - plain text
• WWW.example.com - plain text

Contributor

• Test(s) exist to ensure functionality and minimize regression (added tests in test/specs/new/autolinks.md and test/specs/new/autolinks.html)
• No new feature documentation required (bug fix only)

Committer

In most cases, this should be a different person than the contributor.

• CI is green (no forced merge required).
• Squash and Merge PR following conventional commit guidelines.

[vercel]

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Project	Deployment	Preview	Comments	Updated (UTC)
marked-website	Ready	Preview	Comment	Oct 4, 2025 6:22am

[gemini-code-assist]

Summary of Changes

Hello @vaskkey, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves an inconsistency in autolink detection for www. prefixes, ensuring its behavior matches GitHub Flavored Markdown. Previously, the system would incorrectly autolink Www. or WWW. due to a global case-insensitive regex. The updated logic now recognizes only the lowercase www. as an autolink start, while maintaining explicit case-insensitivity for protocol prefixes like http or ftp. This change improves the accuracy and consistency of Markdown rendering.

Highlights

• Autolink Detection Consistency: Standardized www. autolink detection to be case-sensitive, aligning with GitHub Flavored Markdown behavior.
• Regex Refinement: The inlineGfm.url regular expression was modified to remove the global case-insensitive flag, while explicitly making protocol detection (e.g., http, ftp) case-insensitive within the pattern.
• Enhanced Test Coverage: New test cases were added to validate the correct autolinking behavior for www., Www., and WWW. prefixes.

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[gemini-code-assist]

Code Review

This pull request correctly addresses the case-sensitivity of www. autolinks to align with GFM behavior. The change in src/rules.ts is logical, and the new tests in autolinks.md and autolinks.html properly cover the intended fix. However, I've identified a significant related issue: the text parsing rule was not updated along with the url rule. This oversight can lead to incorrect parsing for URLs that use uppercase protocols when they are preceded by other text. I've left a detailed comment on this issue.

[vercel]

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[UziTech]

/gemini review

[gemini-code-assist]

Code Review

This pull request correctly addresses the case-sensitivity of www. autolinks by removing the case-insensitive flag from the URL regex and explicitly handling case-insensitivity for protocols like http and ftp. The addition of test cases is great for ensuring the fix is working as expected and preventing regressions. I have one minor suggestion in src/rules.ts to improve code maintainability by removing a small inconsistency and duplication.

[UziTech]

Thanks 💯