Inferno vs Preact vs React-DOM: Architecture and API Compared

react-dom, preact, and inferno all solve the same fundamental problem: efficiently updating the browser DOM in response to state changes. However, they make different trade-offs regarding API compatibility, bundle weight, and runtime performance. Let's compare how they handle component rendering, state management, and DOM hydration.

🏗️ Component Definition and Rendering

react-dom uses the standard React API. You define components using functions or classes and mount them using createRoot.

// react-dom: Standard component
import { createRoot } from 'react-dom/client';

function App({ message }) {
  return <div className="app">{message}</div>;
}

const root = createRoot(document.getElementById('root'));
root.render(<App message="Hello React" />);

preact mirrors the React API closely. You can use JSX directly, and the render method is similar but imports from preact.

// preact: Compatible component
import { render } from 'preact';

function App({ message }) {
  return <div className="app">{message}</div>;
}

render(<App message="Hello Preact" />, document.getElementById('root'));

inferno requires specific imports and historically encouraged using createVNode for optimization, though JSX is supported via babel plugins.

// inferno: Optimized component
import { render } from 'inferno';

function App({ message }) {
  return <div className="app">{message}</div>;
}

render(<App message="Hello Inferno" />, document.getElementById('root'));

🔄 State Management and Hooks

react-dom supports the full Hooks API (useState, useEffect, etc.) out of the box. It relies on the Fiber architecture for scheduling updates.

// react-dom: Hooks
import { useState } from 'react';

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

preact includes a compatible Hooks implementation. For most use cases, it behaves identically to React, though edge cases in complex effect dependencies may differ slightly.

// preact: Hooks
import { useState } from 'preact/hooks';

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

inferno supports hooks via inferno-hooks. It is optimized for speed but requires strict adherence to rules of hooks to maintain performance gains.

// inferno: Hooks
import { useState } from 'inferno-hooks';

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

🧩 Compatibility with React Ecosystem

react-dom is the reference implementation. All React libraries work here by default.

// react-dom: Native compatibility
import { BrowserRouter } from 'react-router-dom';
// Works without configuration

preact uses an alias preact/compat to map React imports to Preact internals. This allows using most React libraries without changes.

// preact: Compatibility layer
// webpack.config.js
resolve: {
  alias: {
    "react": "preact/compat",
    "react-dom": "preact/compat"
  }
}
// Now react-router-dom works

inferno has inferno-compat but it is less comprehensive than Preact's. Some complex React libraries may break or require patches.

// inferno: Limited compatibility
import { render } from 'inferno-compat';
// Some React libraries may not function correctly
// due to differences in internal implementation

⚡ Performance Optimization Strategies

react-dom relies on the Fiber reconciler to prioritize updates. You optimize using React.memo or useMemo.

// react-dom: Memoization
import { memo } from 'react';

const ExpensiveComponent = memo(function({ data }) {
  return <div>{data}</div>;
});

preact is fast by default due to its smaller size. It also supports memo but often needs less optimization for similar results.

// preact: Memoization
import { memo } from 'preact/compat';

const ExpensiveComponent = memo(function({ data }) {
  return <div>{data}</div>;
});

inferno uses flags on VNodes to skip diffing entirely if content is static. This requires developer awareness of data mutability.

// inferno: VNode Flags
import { createVNode, VNodeFlags } from 'inferno';

// Manually optimizing a static node
const vnode = createVNode(
  VNodeFlags.HtmlElement, 
  'div', 
  'className', 
  'Static Content'
);

🌐 Server-Side Rendering (SSR)

react-dom uses react-dom/server for streaming or static HTML generation.

// react-dom: SSR
import { renderToPipeableStream } from 'react-dom/server';

stream = renderToPipeableStream(<App />, { onShellReady() {...} });

preact provides preact-render-to-string which is synchronous and very fast.

// preact: SSR
import render from 'preact-render-to-string';

const html = render(<App />);

inferno uses inferno-server for rendering. It focuses on speed and checksum validation.

// inferno: SSR
import { renderToString } from 'inferno-server';

const html = renderToString(<App />);

🤝 Similarities: Shared Ground

While the implementations differ, all three libraries share core concepts that make migration possible.

1. ⚛️ Component-Based Architecture

• All use functional or class components.
• All rely on a virtual DOM (or similar abstraction) to batch updates.

// Shared pattern
function Component({ prop }) {
  return <div>{prop}</div>;
}

2. 🎣 Hooks Support

• All support useState, useEffect, and useContext.
• Logic reuse is possible across all three with minor import changes.

// Shared hook usage
const [val, setVal] = useState(initial);

3. 🔌 JSX Syntax

• All require a build step to transform JSX into JavaScript calls.
• Syntax is nearly identical, though class vs className may vary in strict modes.

// Shared JSX
<div className="container">Content</div>

📊 Summary: Key Differences

💡 The Big Picture

react-dom is the industry standard 🏛️. It is the safest bet for long-term projects, hiring, and ecosystem integration. Choose this unless you have a specific reason not to.

preact is the pragmatic lightweight alternative 🕊️. It offers the best balance of size and compatibility. If you need to shave off kilobytes but keep your React code, this is the winner.

inferno is the specialist tool 🛠️. It offers raw speed but demands more from the developer regarding optimization patterns. Use it only when you have profiled your app and identified the renderer as the bottleneck.

Final Thought: For 95% of projects, react-dom or preact will serve you best. inferno remains a powerful option for specific high-performance niches but requires more maintenance overhead.