TypeScriptNext.jsTypeScript
1/15/2024
Next.js 15 App Router TypeScript Best Practices

Comprehensive TypeScript rules for Next.js 15 with App Router. Includes server components, client components, route handlers, and middleware patterns with strict type safety.

AJ

Alex Johnson

@alexj

Next.jsTypeScriptApp RouterReact
You are an expert in TypeScript, Node.js, Next.js App Router, React, Shadcn UI, Radix UI and Tailwind.

Code Style and Structure
- Write concise, technical TypeScript code with accurate examples.
- Use functional and declarative programming patterns; avoid classes.
- Prefer iteration and modularization over code duplication.
- Use descriptive variable names with auxiliary verbs (e.g., isLoading, hasError).
- Structure files: exported component, subcomponents, helpers, static content, types.

Naming Conventions
- Use lowercase with dashes for directories (e.g., components/auth-wizard).
- Favor named exports for components.

TypeScript Usage
- Use TypeScript for all code; prefer interfaces over types.
- Avoid enums; use maps or objects with 'as const' assertion.
- Use functional components with TypeScript interfaces.

Syntax and Formatting
- Use the "function" keyword for pure functions.
- Avoid unnecessary curly braces in conditionals; use concise syntax for simple statements.
- Use declarative JSX.

UI and Styling
- Use Shadcn UI, Radix, and Tailwind for components and styling.
- Implement responsive design with Tailwind CSS; use a mobile-first approach.

Performance Optimization
- Minimize 'use client', 'useEffect', and 'useState'; favor React Server Components (RSC).
- Wrap client components in Suspense with fallback.
- Use dynamic loading for non-critical components.
- Optimize images: use WebP format, include size data, implement lazy loading.

Key Conventions
- Use 'nuqs' for URL search parameter state management.
- Optimize Web Vitals (LCP, CLS, FID).
- Limit 'use client':
  - Favor server components and Next.js SSR.
  - Use only for Web API access in small components.
  - Avoid for data fetching or state management.

Follow Next.js docs for Data Fetching, Rendering, and Routing.
Comments (3)4 total
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SJ
Sarah Johnson@sarahj1/16/2024

This is an excellent rule set! I've been using it for my Next.js projects and it's really improved my code quality. The TypeScript configurations are spot on.

12
MC
Mike Chen@mikechen1/16/2024

I agree! The server component patterns are particularly helpful.

5
DR
David Rodriguez@davidr1/16/2024

Could you add some examples for error handling patterns? That would make this rule set even more comprehensive.

8
LP
Lisa Park@lisapark1/16/2024

Thanks for sharing this! One question - do you have any recommendations for testing patterns that work well with these rules?

3