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Blocked Links

Testing & Quality
blocked-links

Blocked Links is an Agent Skill for testing & quality published in the thedaviddias/Front-End-Checklist repository on GitHub: a SKILL.md instruction file an AI agent can load to do this task.

Use when reviewing HTML source and JavaScript for links or resource URLs pointing to domains listed in common adblocker filter lists.

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QUICK START

How to use this skill

Bring this guide into your coding agent with a prompt tailored to the tool you use.

  1. Open your project in Codex.
  2. Copy and paste the prompt below.
  3. Review files and risks before approving any action.
Prompt to paste
Inspect the Agent Skill at https://github.com/thedaviddias/Front-End-Checklist/blob/HEAD/skills/blocked-links/SKILL.md and all supporting files. Report provenance, permissions, scripts, dependencies, and security risks. Propose an exact installation into .agents/skills/blocked-links, but wait for my approval before writing files or running scripts.

Copying this prompt does not install or run the skill. Review third-party files before use.

Blocked Tracking Links

When a navigation link's URL matches a tracking domain pattern, the adblocker may block the request entirely — the user clicks the link and nothing happens, breaking core site functionality.

Quick Reference

  • Adblockers block URLs matching domain-level filter lists like EasyList and EasyPrivacy
  • Affected resources include external scripts, images, fonts, and API endpoints hosted on blocked domains
  • Analytics and tag management scripts (Google Analytics, GTM, Hotjar, Heap) are commonly blocked
  • Self-hosting or proxying external scripts through your own domain bypasses most domain-level blocks
  • 20–40% of desktop users have an adblocker installed — blocked analytics skews your data significantly

Check

Identify external script sources, image src URLs, iframe src URLs, and anchor href values that point to known tracking domains (googletagmanager.com, hotjar.com, facebook.net, doubleclick.net, etc.). Test whether these resources load successfully with uBlock Origin enabled.

Fix

Self-host critical external scripts on your own domain. Use a reverse proxy or server-side route to forward requests to third-party analytics APIs. For navigation links, avoid using tracking redirect URLs — use direct destination URLs with UTM parameters appended instead.

Explain

Explain how domain-level adblocker filter lists work, which domains are commonly blocked, how blocked resources affect site functionality and analytics accuracy, and the self-hosting approach to bypass domain blocks.

Code Review

Review server config, headers, forms, and integration points related to Blocked Tracking Links. Flag exact responses, cookies, or browser behaviors that violate the rule, and verify them against the effective production-like response.

For full implementation details, code examples, and framework-specific guidance, see references/rule.md.

Rule page: https://frontendchecklist.io/en/rules/security/blocked-links