Frontend Development Guidelines

Purpose

Comprehensive guide for modern React development, emphasizing Suspense-based data fetching, lazy loading, proper file organization, and performance optimization.

When to Use This Skill

Creating new components or pages
Building new features
Fetching data with TanStack Query
Setting up routing with TanStack Router
Styling components with MUI v7
Performance optimization
Organizing frontend code
TypeScript best practices

Quick Start

New Component Checklist

Creating a component? Follow this checklist:

New Feature Checklist

Creating a feature? Set up this structure:

Create features/{feature-name}/ directory
Create subdirectories: api/, components/, hooks/, helpers/, types/
Create API service file: api/{feature}Api.ts
Set up TypeScript types in types/
Create route in routes/{feature-name}/index.tsx
Lazy load feature components
Use Suspense boundaries
Export public API from feature index.ts

Import Aliases Quick Reference

Alias	Resolves To	Example
`@/`	`src/`	`import { apiClient } from '@/lib/apiClient'`
`~types`	`src/types`	`import type { User } from '~types/user'`
`~components`	`src/components`	`import { SuspenseLoader } from '~components/SuspenseLoader'`
`~features`	`src/features`	`import { authApi } from '~features/auth'`

Defined in: vite.config.ts lines 180-185

Common Imports Cheatsheet

// React & Lazy Loading
import React, { useState, useCallback, useMemo } from 'react';
const Heavy = React.lazy(() => import('./Heavy'));

// MUI Components
import { Box, Paper, Typography, Button, Grid } from '@mui/material';
import type { SxProps, Theme } from '@mui/material';

// TanStack Query (Suspense)
import { useSuspenseQuery, useQueryClient } from '@tanstack/react-query';

// TanStack Router
import { createFileRoute } from '@tanstack/react-router';

// Project Components
import { SuspenseLoader } from '~components/SuspenseLoader';

// Hooks
import { useAuth } from '@/hooks/useAuth';
import { useMuiSnackbar } from '@/hooks/useMuiSnackbar';

// Types
import type { Post } from '~types/post';

Topic Guides

🎨 Component Patterns

Modern React components use:

React.FC<Props> for type safety
React.lazy() for code splitting
SuspenseLoader for loading states
Named const + default export pattern

Key Concepts:

Lazy load heavy components (DataGrid, charts, editors)
Always wrap lazy components in Suspense
Use SuspenseLoader component (with fade animation)
Component structure: Props → Hooks → Handlers → Render → Export

📖 Complete Guide: resources/component-patterns.md

📊 Data Fetching

PRIMARY PATTERN: useSuspenseQuery

Use with Suspense boundaries
Cache-first strategy (check grid cache before API)
Replaces isLoading checks
Type-safe with generics

API Service Layer:

Create features/{feature}/api/{feature}Api.ts
Use apiClient axios instance
Centralized methods per feature
Route format: /form/route (NOT /api/form/route)

📖 Complete Guide: resources/data-fetching.md

📁 File Organization

features/ vs components/:

features/: Domain-specific (posts, comments, auth)
components/: Truly reusable (SuspenseLoader, CustomAppBar)

Feature Subdirectories:

features/
  my-feature/
    api/          # API service layer
    components/   # Feature components
    hooks/        # Custom hooks
    helpers/      # Utility functions
    types/        # TypeScript types

📖 Complete Guide: resources/file-organization.md

🎨 Styling

Inline vs Separate:

<100 lines: Inline const styles: Record<string, SxProps<Theme>>
100 lines: Separate .styles.ts file

Primary Method:

Use sx prop for MUI components
Type-safe with SxProps<Theme>
Theme access: (theme) => theme.palette.primary.main

MUI v7 Grid:

<Grid size={{ xs: 12, md: 6 }}>  // ✅ v7 syntax
<Grid xs={12} md={6}>             // ❌ Old syntax

📖 Complete Guide: resources/styling-guide.md

🛣️ Routing

TanStack Router - Folder-Based:

Directory: routes/my-route/index.tsx
Lazy load components
Use createFileRoute
Breadcrumb data in loader

Example:

import { createFileRoute } from '@tanstack/react-router';
import { lazy } from 'react';

const MyPage = lazy(() => import('@/features/my-feature/components/MyPage'));

export const Route = createFileRoute('/my-route/')({
    component: MyPage,
    loader: () => ({ crumb: 'My Route' }),
});

📖 Complete Guide: resources/routing-guide.md

⏳ Loading & Error States

Rule: No Early Returns

// ❌ Avoid - Causes layout shift
if (isLoading) {
    return <LoadingSpinner />;
}

// ✅ Better - Consistent layout
<SuspenseLoader>
    <Content />
</SuspenseLoader>

Why: Prevents Cumulative Layout Shift (CLS), better UX

Error Handling:

Use useMuiSnackbar for user feedback
Avoid react-toastify
TanStack Query onError callbacks

📖 Complete Guide: resources/loading-and-error-states.md

⚡ Performance

Optimization Patterns:

useMemo: Expensive computations (filter, sort, map)
useCallback: Event handlers passed to children
React.memo: Expensive components
Debounced search (300-500ms)
Memory leak prevention (cleanup in useEffect)

📖 Complete Guide: resources/performance.md

📘 TypeScript

Standards:

Strict mode, no any type
Explicit return types on functions
Type imports: import type { User } from '~types/user'
Component prop interfaces with JSDoc

📖 Complete Guide: resources/typescript-standards.md

🔧 Common Patterns

Covered Topics:

React Hook Form with Zod validation
DataGrid wrapper contracts
Dialog component standards
useAuth hook for current user
Mutation patterns with cache invalidation

📖 Complete Guide: resources/common-patterns.md

📚 Complete Examples

Full working examples:

Modern component with all patterns
Complete feature structure
API service layer
Route with lazy loading
Suspense + useSuspenseQuery
Form with validation

📖 Complete Guide: resources/complete-examples.md

Navigation Guide

Need to...	Read this resource
Create a component	component-patterns.md
Fetch data	data-fetching.md
Organize files/folders	file-organization.md
Style components	styling-guide.md
Set up routing	routing-guide.md
Handle loading/errors	loading-and-error-states.md
Optimize performance	performance.md
TypeScript types	typescript-standards.md
Forms/Auth/DataGrid	common-patterns.md
See full examples	complete-examples.md

Core Principles

Lazy Load Everything Heavy: Routes, DataGrid, charts, editors
Suspense for Loading: Use SuspenseLoader, not early returns
useSuspenseQuery: Primary data fetching pattern for new code
Features are Organized: api/, components/, hooks/, helpers/ subdirs
Styles Based on Size: <100 inline, >100 separate
Import Aliases: Use @/, ~types, ~components, ~features
No Early Returns: Prevents layout shift
useMuiSnackbar: For all user notifications
Avoid Over-Engineering: Only make changes directly requested or clearly necessary. Keep solutions simple and focused. Do not add features or refactor code beyond what was asked.
Read Before Editing: Understand relevant files before proposing code edits. Do not speculate about code not inspected.

Quick Reference: File Structure

src/
  features/
    my-feature/
      api/
        myFeatureApi.ts       # API service
      components/
        MyFeature.tsx         # Main component
        SubComponent.tsx      # Related components
      hooks/
        useMyFeature.ts       # Custom hooks
        useSuspenseMyFeature.ts  # Suspense hooks
      helpers/
        myFeatureHelpers.ts   # Utilities
      types/
        index.ts              # TypeScript types
      index.ts                # Public exports

  components/
    SuspenseLoader/
      SuspenseLoader.tsx      # Reusable loader
    CustomAppBar/
      CustomAppBar.tsx        # Reusable app bar

  routes/
    my-route/
      index.tsx               # Route component
      create/
        index.tsx             # Nested route

Modern Component Template (Quick Copy)

import React, { useState, useCallback } from 'react';
import { Box, Paper } from '@mui/material';
import { useSuspenseQuery } from '@tanstack/react-query';
import { featureApi } from '../api/featureApi';
import type { FeatureData } from '~types/feature';

interface MyComponentProps {
    id: number;
    onAction?: () => void;
}

export const MyComponent: React.FC<MyComponentProps> = ({ id, onAction }) => {
    const [state, setState] = useState<string>('');

    const { data } = useSuspenseQuery({
        queryKey: ['feature', id],
        queryFn: () => featureApi.getFeature(id),
    });

    const handleAction = useCallback(() => {
        setState('updated');
        onAction?.();
    }, [onAction]);

    return (
        <Box sx={{ p: 2 }}>
            <Paper sx={{ p: 3 }}>
                {/* Content */}
            </Paper>
        </Box>
    );
};

export default MyComponent;

For complete examples, see resources/complete-examples.md

Related Skills

error-tracking: Error tracking with Sentry (applies to frontend too)
backend-dev-guidelines: Backend API patterns that frontend consumes

Skill Status: Modular structure with progressive loading for optimal context management

frontend-dev-guidelines