React vs Angular: Architectural Differences, Pros and Cons for Modern Web Development

React offers a flexible, lightweight virtual DOM with Fiber-based concurrent rendering, while Angular delivers a comprehensive, TypeScript-first framework with real DOM updates, built-in dependency injection, and RxJS-based reactivity.

When evaluating frontend frameworks for your next project, understanding the fundamental architectural differences between Facebook's React and Google's Angular is crucial. This analysis examines the source code of the React repository to explain how React's minimalist, concurrent rendering model contrasts with Angular's all-in-one approach, helping you decide which better fits your team's needs.

Virtual DOM vs. Real DOM: Core Rendering Models

React's Virtual DOM and Fiber Architecture

React builds a lightweight virtual DOM tree that serves as an in-memory representation of the actual UI. In packages/react/src/jsx/ReactJSXElement.js, the createElement function constructs these virtual nodes, which React then diffs against the previous render to calculate minimal real-DOM mutations.

The Fiber architecture—visible in packages/react/src/ReactStartTransition.js—breaks rendering work into units that can be paused, aborted, or spread across frames. This enables concurrent rendering, allowing React to keep the UI responsive during expensive updates by marking transitions as low-priority.

import {useState, startTransition} from 'react';

function ExpensiveList({items}) {
  const [list, setList] = useState(items);
  
  const update = (newItems) => {
    startTransition(() => {
      setList(newItems);
    });
  };

  return <ul>{list.map(i => <li key={i}>{i}</li>)}</ul>;
}

Angular's Change Detection Strategy

Angular uses real DOM updates driven by a zone-based change-detection mechanism. Unlike React's diffing algorithm, Angular runs synchronous checks after async events, comparing component template bindings to current values. While Angular lacks React's built-in cooperative scheduler, it offers Ahead-of-Time (AOT) compilation that converts templates into optimized DOM manipulation instructions at build time.

Component Architecture and State Management

Function Components and Hooks in React

React supports both class components (defined in packages/react/src/ReactBaseClasses.js) and function components, with hooks now being the preferred pattern. The useState implementation in packages/react/src/ReactHooks.js stores state directly in the Fiber associated with the component, eliminating the need for lifecycle methods.

JSX provides syntactic sugar for React.createElement, living alongside standard JavaScript without requiring a separate template DSL:

import {useState} from 'react';

function Counter() {
  const [count, setCount] = useState(0);
  return (
    <button onClick={() => setCount(c => c + 1)}>
      Count: {count}
    </button>
  );
}

Class-Based Components and Dependency Injection in Angular

Angular relies exclusively on class-based components with decorators (@Component), coupled with a powerful hierarchical dependency injection container. Rather than React's props drilling or Context API (implemented in packages/react/src/ReactContext.js), Angular injects services directly into component constructors.

State management typically leverages RxJS observables, providing reactive streams for complex data flows that React handles through external libraries like Redux or Recoil.

import {Component} from '@angular/core';

@Component({
  selector: 'app-counter',
  template: `
    <button (click)="increment()">
      Count: {{count}}
    </button>
  `,
})
export class CounterComponent {
  count = 0;
  increment() {
    this.count++;
  }
}

Performance Characteristics

Concurrent Rendering and Bundle Size

React ships as a small core (~30 KB gzipped), requiring developers to opt into routing and state management. The Fiber architecture enables features like startTransition, which marks state updates as interruptible to maintain responsiveness during heavy renders.

Angular delivers a full-featured framework (~70 KB gzipped) including router, forms, HTTP client, and RxJS. While this increases initial bundle size, it eliminates decision fatigue regarding third-party selections.

Change Detection Optimization

React's targeted diffing updates only components that changed, while Angular's default change detection runs globally after every async event. Large Angular applications require manual optimization using OnPush strategy or detach methods to prevent performance degradation, whereas React's reconciliation automatically minimizes DOM operations.

Developer Experience and Ecosystem

Flexibility vs. Convention

React offers minimal core APIs with no prescribed patterns for state management or routing. This flexibility allows architects to customize stacks but can lead to inconsistency across teams. The lack of built-in dependency injection means code sharing relies on props, custom hooks, or the Context API.

Angular enforces strong conventions through its CLI and TypeScript-first architecture. The framework's opinionated structure—including built-in forms validation, HTTP clients, and router—accelerates standardization but may constrain unconventional architectures.

Learning Curve and Tooling

Developers can begin with React using plain JavaScript and JSX, advancing to complex patterns like concurrent mode incrementally. Angular requires upfront knowledge of TypeScript, decorators, and RxJS observables, creating a steeper initial learning curve but providing comprehensive tooling through the Angular CLI.

Summary

• React utilizes a virtual DOM with Fiber-based concurrent rendering, offering fine-grained updates and a small bundle footprint (~30 KB) at the cost of requiring third-party solutions for routing and state.
• Angular provides real DOM updates with built-in dependency injection, RxJS reactivity, and comprehensive tooling, but requires optimization strategies like OnPush change detection and carries a larger initial bundle (~70 KB).
• React's JSX integrates directly with JavaScript, while Angular uses a separate template DSL requiring compilation.
• Fiber enables interruptible rendering in React; Angular's change detection runs synchronously without a built-in cooperative scheduler.
• React offers maximum flexibility with minimal opinions; Angular delivers an all-in-one, convention-driven framework.

Frequently Asked Questions

Which framework has better performance, React or Angular?

React's Fiber architecture generally provides superior UI responsiveness during heavy updates through concurrent rendering and automatic diffing, while Angular requires manual optimization using OnPush change detection to prevent synchronous blocking. However, Angular's AOT compilation and tree-shaking can deliver excellent runtime performance for static content when properly configured.

Is React or Angular easier to learn for beginners?

React presents a gentler initial learning curve because developers can start with basic JavaScript and JSX without mastering TypeScript or reactive programming concepts. Angular demands immediate familiarity with TypeScript decorators, RxJS observables, and dependency injection patterns, making the initial barrier to entry higher despite its comprehensive documentation.

How do the bundle sizes compare between React and Angular?

React's core library is significantly smaller (~30 KB gzipped) but rarely functions alone in production applications, typically requiring additional libraries for routing and state management. Angular ships as a complete solution (~70 KB gzipped) including router, forms, and HTTP client, which may result in larger initial bundles but predictable total payload sizes.

Which is better for large enterprise applications, React or Angular?

Angular often suits large enterprises better due to its built-in dependency injection, strict TypeScript integration, and standardized CLI that enforces architectural consistency across teams. React can scale effectively but requires deliberate architectural decisions regarding state management and code organization to maintain consistency in large codebases.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}