---name: senior-frontenddescription: Frontend development skill for React, Next.js, TypeScript, and Tailwind CSS applications. Use when building React components, optimizing Next.js performance, analyzing bundle sizes, scaffolding frontend projects, implementing accessibility, or reviewing frontend code quality.---

Senior Frontend

Frontend development patterns, performance optimization, and automation tools for React/Next.js applications.

Project Scaffolding

Generate a new Next.js or React project with TypeScript, Tailwind CSS, and best practice configurations.

Scaffolder Options

Option	Description
--template nextjs	Next.js 14+ with App Router and Server Components
--template react	React + Vite with TypeScript
--features auth	Add NextAuth.js authentication
--features api	Add React Query + API client
--features forms	Add React Hook Form + Zod validation
--features testing	Add Vitest + Testing Library

Generated Structure (Next.js)

my-app/
├── app/
│   ├── layout.tsx        # Root layout with fonts
│   ├── page.tsx          # Home page
│   ├── globals.css       # Tailwind + CSS variables
│   └── api/health/route.ts
├── components/
│   ├── ui/               # Button, Input, Card
│   └── layout/           # Header, Footer, Sidebar
├── hooks/                # useDebounce, useLocalStorage
├── lib/                  # utils (cn), constants
├── types/                # TypeScript interfaces
├── tailwind.config.ts
├── next.config.js
└── package.json

Component Generation

Generate React components with TypeScript, tests, and Storybook stories.

Generator Options

Option	Description
--type client	Client component with 'use client' (default)
--type server	Async server component
--type hook	Custom React hook
--with-test	Include test file
--with-story	Include Storybook story

Bundle Analysis

Analyze package.json and project structure for bundle optimization opportunities.

Heavy Dependencies to Replace

Package	Size	Alternative
moment	290KB	date-fns (12KB) or dayjs (2KB)
lodash	71KB	lodash-es with tree-shaking
axios	14KB	Native fetch or ky (3KB)
jquery	87KB	Native DOM APIs
@mui/material	Large	shadcn/ui or Radix UI

React Patterns

Compound Components

const Tabs = ({ children }) => {
  const [active, setActive] = useState(0);
  return (
    <TabsContext.Provider value={{ active, setActive }}>
      {children}
    </TabsContext.Provider>
  );
};

Tabs.List = TabList;
Tabs.Panel = TabPanel;

Custom Hooks

function useDebounce<T>(value: T, delay = 500): T {
  const [debouncedValue, setDebouncedValue] = useState(value);

  useEffect(() => {
    const timer = setTimeout(() => setDebouncedValue(value), delay);
    return () => clearTimeout(timer);
  }, [value, delay]);

  return debouncedValue;
}

Next.js Optimization

Server vs Client Components

Use Server Components by default. Add 'use client' only when you need:

• Event handlers (onClick, onChange)
• State (useState, useReducer)
• Effects (useEffect)
• Browser APIs

Image Optimization

import Image from 'next/image';

// Above the fold - load immediately
<Image
  src="/hero.jpg"
  alt="Hero"
  width={1200}
  height={600}
  priority
/>

// Responsive image with fill
<div className="relative aspect-video">
  <Image
    src="/product.jpg"
    alt="Product"
    fill
    sizes="(max-width: 768px) 100vw, 50vw"
    className="object-cover"
  />
</div>

Accessibility Checklist

1. Semantic HTML: Use proper elements (<button>, <nav>, <main>)
2. Keyboard Navigation: All interactive elements focusable
3. ARIA Labels: Provide labels for icons and complex widgets
4. Color Contrast: Minimum 4.5:1 for normal text
5. Focus Indicators: Visible focus states

// Accessible button
<button
  type="button"
  aria-label="Close dialog"
  onClick={onClose}
  className="focus-visible:ring-2 focus-visible:ring-blue-500"
>
  <XIcon aria-hidden="true" />
</button>

Quick Reference

Tailwind CSS Utilities

import { cn } from '@/lib/utils';

<button className={cn(
  'px-4 py-2 rounded',
  variant === 'primary' && 'bg-blue-500 text-white',
  disabled && 'opacity-50 cursor-not-allowed'
)} />

TypeScript Patterns

// Props with children
interface CardProps {
  className?: string;
  children: React.ReactNode;
}

// Generic component
interface ListProps<T> {
  items: T[];
  renderItem: (item: T) => React.ReactNode;
}

function List<T>({ items, renderItem }: ListProps<T>) {
  return <ul>{items.map(renderItem)}</ul>;
}