Find JavaScript that executes strings as code, including eval(), new Function(), and string-based timers. Review how it runs in the browser and suggest alternatives for parsing data, choosing operations, and scheduling functions to reduce code injection risks.
Use when reviewing scripts, client components, bundles, or runtime behavior related to Never use eval() or unsafe dynamic code execution. Inspect both source code and the browser execution path so fixes target the real bottleneck or bug.
Review the instructions the agent will receive before you install.
eval() and its equivalents are the root cause of some of the most severe XSS vulnerabilities. If any user-controlled string reaches eval(), an attacker can execute arbitrary JavaScript in your users' browsers — stealing sessions, making requests as the user, or redirecting to malicious sites. Content Security Policy (CSP) blocks eval() but not new Function(), and there is never a legitimate use case that can't be solved without it.
Search this codebase for any use of eval(), new Function(), or setTimeout/setInterval with string arguments.
Replace eval() calls with safe alternatives: JSON.parse for data, object lookups for dynamic dispatch, and Function references for timers.
Explain why eval() is dangerous, how it enables XSS attacks, and what safe alternatives exist for each use case.
Review scripts, client components, and browser execution paths related to Never use eval() or unsafe dynamic code execution. Flag exact imports, event handlers, runtime side effects, or blocking operations that violate the rule, and state how the change should be verified in the browser.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/rules/javascript/avoid-eval
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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.