Review cross-origin isolation, a browser security mode required by features such as SharedArrayBuffer. Check response headers and external resources, identify integrations that could break, and verify that isolation actually works in the browser.
Use when reviewing security-sensitive web apps, SharedArrayBuffer usage, worker-heavy apps, editors, or measurement features that require cross-origin isolation. Check both headers and real browser behavior.
Review the instructions the agent will receive before you install.
Cross-origin isolation reduces opener-based attacks and XS-Leak risk, and it is required for powerful browser features such as SharedArrayBuffer in modern browsers. It also breaks integrations if deployed carelessly, so it needs a deliberate rollout rather than a copy-pasted header block.
Cross-Origin-Opener-Policy and Cross-Origin-Embedder-Policy together when you need cross-origin isolationCross-Origin-Resource-Policy as appropriateself.crossOriginIsolated === true before depending on isolated-only featuresReview security headers and embedded resources for cross-origin isolation. Check whether the app needs COOP/COEP, whether resources are compatible with COEP, and whether the runtime actually becomes crossOriginIsolated.
Add COOP and COEP only after auditing dependencies, ensure subresources use CORP or CORS as required, and verify the final document becomes crossOriginIsolated in the browser.
Explain how COOP, COEP, and CORP work together, what they protect against, and why third-party embeds often block a successful rollout.
Review server headers, third-party integrations, popups, workers, and asset responses related to Use COOP, COEP, and CORP for cross-origin isolation when needed. Flag exact responses or integrations that would block isolation or break once isolation is enforced.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/rules/security/cross-origin-isolation
No reviews yet. Tell others what you thought.
No login needed. Share how it worked for you, ask a question, or note where it did not run.
No comments yet. Be the first to write one.
Create and review custom 404 pages that help visitors recover from broken or moved links through search and navigation. Check the rendered page and HTTP response so missing content returns a proper 404 status.
Audit or create a dedicated About page that explains a website’s purpose and identifies its people or organization. Review the rendered output and supporting information, including expertise and contact details, to find gaps.
Review and add automated accessibility checks for components, pages, and continuous integration workflows. Use axe-based tools to detect structural and attribute issues, while identifying checks that still need keyboard or screen reader testing.
Review sign-in, registration, multi-factor authentication, and account recovery for accessibility barriers. Find blocked paste, difficult code entry, and inaccessible backup methods, then suggest authentication paths that support password managers, autofill, or device approval.
Review form errors, success messages, and live updates so screen reader users receive important notifications. Check the HTML delivered to the browser, announcement settings, display duration, and dismissal controls, then identify specific elements that need changes.
Review HTML tables so screen reader users can understand how headers and data relate. Check header markup, table descriptions, and merged cells, then identify specific fixes and ways to verify them.