Review large JavaScript bundles to find code that can load later. Suggest dynamic imports, which load modules when needed, and page-level splitting, with loading states for heavy libraries and features outside the initial view.
Use when reviewing large SPA bundles, new dependency additions, or routes that feel slow to hydrate. Focus on code that is not required for the initial view and can move behind route transitions, user interaction, or viewport-based loading.
Review the instructions the agent will receive before you install.
A 500 KB JavaScript bundle blocks page interactivity for 3–5 seconds on a mid-range mobile device even after the bytes arrive — JS must be parsed and compiled before execution. Code splitting means users only download and parse the code they actually need for the current page, dramatically improving Time to Interactive.
Identify any large third-party imports or feature modules in this file that could be loaded lazily with dynamic import() instead of statically.
Convert the identified static imports to dynamic imports using import() and add appropriate loading states.
Explain JavaScript code splitting, how dynamic import() works, and how to implement route-based splitting in a SPA.
Inspect route modules, heavy feature imports, and third-party libraries loaded on initial render. Flag dependencies that can move behind import(), route boundaries, or user-triggered flows without breaking the first meaningful paint.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/rules/javascript/code-splitting
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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.