Building Scalable React Applications

React has become the standard for building modern web applications, but with great power comes the responsibility of architecture. When a project grows from a small prototype to a large-scale enterprise application, the initial decisions you make about structure and patterns become critical.

In this guide, I'll walk you through the proven patterns and practices that I use to build scalable React applications that are easy to maintain and performant.

Organizing Your Project Structure

One of the first challenges developers face is how to organize files. A "feature-based" structure is often superior to grouping by file type (like putting all components in one folder).

By grouping related files together by feature, you make it easier to delete code when a feature is removed, and you keep related logic close together.

bash

src/
├── components/     # Shared, generic UI components (Buttons, Inputs)
├── features/       # Feature-based modules (Auth, UserProfile, Dashboard)
│   ├── auth/
│   │   ├── components/
│   │   ├── hooks/
│   │   └── api/
├── hooks/          # Global custom React hooks
├── services/       # Global API and business logic
├── utils/          # Helper functions
└── types/          # Shared TypeScript definitions

Encapsulating Logic with Custom Hooks

A common mistake is writing too much logic inside components. This makes components hard to read and test. Instead, you should extract complex logic into Custom Hooks.

Custom hooks allow you to reuse stateful logic without changing your component hierarchy. They also make your components purely presentational.

Here is an example of a custom hook that handles data fetching with loading and error states:

typescript

// hooks/useApi.ts
import { useState, useEffect } from 'react';

export function useApi<T>(url: string) {
  const [data, setData] = useState<T | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<Error | null>(null);

  useEffect(() => {
    const fetchData = async () => {
      try {
        setLoading(true);
        const response = await fetch(url);
        const json = await response.json();
        setData(json);
      } catch (err) {
        setError(err as Error);
      } finally {
        setLoading(false);
      }
    };

    fetchData();
  }, [url]);

  return { data, loading, error };
}

The Compound Component Pattern

When building reusable UI libraries, you often need components that work together. The Compound Component Pattern is an excellent way to achieve this. It allows you to create a parent component that implicitly shares state with its children, providing a flexible API for the user.

For example, instead of passing a million props to a Card component, you can compose it like this:

tsx

// Usage
<Card>
  <Card.Header>Title</Card.Header>
  <Card.Body>Content goes here</Card.Body>
</Card>

Here is how you implement it:

tsx

// components/Card.tsx
import { createContext, useContext, ReactNode } from 'react';

// 1. Create a context
const CardContext = createContext<{ variant: string }>({ variant: 'default' });

// 2. Create the parent component
export function Card({ children, variant = 'default' }: { 
  children: ReactNode; 
  variant?: string;
}) {
  return (
    <CardContext.Provider value={{ variant }}>
      <div className={`card card-${variant}`}>{children}</div>
    </CardContext.Provider>
  );
}

// 3. Create child components attached to the parent
Card.Header = function CardHeader({ children }: { children: ReactNode }) {
  return <div className="card-header">{children}</div>;
};

Card.Body = function CardBody({ children }: { children: ReactNode }) {
  return <div className="card-body">{children}</div>;
};

Optimizing Performance

React is fast by default, but unnecessary re-renders can slow down large apps. Virtualization and memoization are key techniques here.

Use React.memo to prevent a component from re-rendering if its props haven't changed. Use useMemo to cache the result of expensive calculations.

tsx

// Memoize expensive computations so they don't run on every render
const sortedItems = useMemo(() => {
  console.log("Sorting items..."); // This only logs when 'data' changes
  return data
    .filter(item => item.active)
    .sort((a, b) => b.value - a.value);
}, [data]);

By following these patterns, you create a codebase that is robust, easy to navigate, and ready for growth.

Building Scalable React Applications: Best Practices for 2024

Building Scalable React Applications

Organizing Your Project Structure

Encapsulating Logic with Custom Hooks

The Compound Component Pattern

Optimizing Performance

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