Learn Inferno - 8 Code Examples & CST Typing Practice Test

Inferno.js is an extremely fast, lightweight JavaScript library for building high-performance user interfaces. It uses a React-like API and Virtual DOM but is optimized for speed, small size, and predictable rendering.

View all 8 Inferno code examples →

Inferno Simple Counter Inferno Counter with Step Inferno Counter with Min/Max Inferno Counter with Auto Increment Inferno Counter with Double Increment Inferno Counter with Even/Odd Indicator Inferno Counter with LocalStorage Inferno Counter with Color Themes

Learn INFERNO with Real Code Examples

Updated Nov 23, 2025

Explain

Inferno provides a React-compatible API focused heavily on performance.

It uses a highly optimized Virtual DOM engine for minimal overhead.

Its architecture makes it suitable for real-time UIs, embedded widgets, and performance-critical apps.

Core Features

JSX + components

Virtual DOM diffing

Lifecycle hooks (componentDidMount, etc.)

Functional components supported

Efficient event handling system

Basic Concepts Overview

JSX + component rendering

Functional and class components

Props + state system

Virtual DOM re-rendering

Event handlers and lifecycle hooks

Project Structure

src/components/ - UI components

src/index.js - app entry

public/index.html - mount point

babel.config.js - JSX transform

vite/webpack config - bundlers

Building Workflow

Create components (functional or class)

Use JSX with Babel or Vite

Render with `Inferno.render()`

Manage state in components

Bundle via Vite/Webpack/Rollup

Difficulty Use Cases

Beginner: simple components

Intermediate: dynamic UIs with state

Advanced: SSR + hydration

Expert: optimizing micro-interactions

Community: custom renderers and extensions

Comparisons

Faster than React - optimized VDOM

Smaller than React - tiny bundle

Less ecosystem than React/Vue

Similar API to React (easy migration)

Better suited for high-performance UIs

Versioning Timeline

2016 - Inferno initial release

2017 - React-like API compatibility

2018 - SSR improvements

2020 - Further performance tuning

2024-2025 - Stable maintenance releases

Glossary

Virtual DOM: lightweight DOM representation

VNode: Virtual DOM node object

Hydration: binding server-rendered HTML

Lifecycle hooks: component methods on render/update

Diffing: comparing VDOM trees efficiently

Code Sample Descriptions

Inferno Simple Counter

import { render, Component } from 'inferno';

class Counter extends Component {
    state = { count: 0, isDark: false };

    increment = () => this.setState({ count: this.state.count + 1 });
    decrement = () => this.setState({ count: this.state.count - 1 });
    reset = () => this.setState({ count: 0 });
    toggleTheme = () => this.setState({ isDark: !this.state.isDark });

    render() {
        return (
        <div className={this.state.isDark ? 'dark-theme' : 'light-theme'}>
        <h2>Counter: {this.state.count}</h2>
        <div>
        <button onClick={this.increment}>+</button>
        <button onClick={this.decrement}>-</button>
        <button onClick={this.reset}>Reset</button>
        </div>
        <button onClick={this.toggleTheme}>Switch to {this.state.isDark ? 'Light' : 'Dark'} Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Basic counter with increment, decrement, reset, and theme toggle.

Let’s Try →

Inferno Counter with Step

import { render, Component } from 'inferno';

class Counter extends Component {
    state = { count: 0, step: 5, isDark: false };

    increment = () => this.setState({ count: this.state.count + this.state.step });
    decrement = () => this.setState({ count: this.state.count - this.state.step });
    reset = () => this.setState({ count: 0 });
    toggleTheme = () => this.setState({ isDark: !this.state.isDark });

    render() {
        return (
        <div className={this.state.isDark ? 'dark-theme' : 'light-theme'}>
        <h2>Counter: {this.state.count}</h2>
        <div>
        <button onClick={this.increment}>+{this.state.step}</button>
        <button onClick={this.decrement}>-{this.state.step}</button>
        <button onClick={this.reset}>Reset</button>
        </div>
        <button onClick={this.toggleTheme}>Switch Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Counter increments/decrements by a custom step value.

Let’s Try →

Inferno Counter with Min/Max

import { render, Component } from 'inferno';

class Counter extends Component {
    state = { count: 0, min: 0, max: 10, isDark: false };

    increment = () => this.setState({ count: Math.min(this.state.count + 1, this.state.max) });
    decrement = () => this.setState({ count: Math.max(this.state.count - 1, this.state.min) });
    reset = () => this.setState({ count: 0 });
    toggleTheme = () => this.setState({ isDark: !this.state.isDark });

    render() {
        return (
        <div className={this.state.isDark ? 'dark-theme' : 'light-theme'}>
        <h2>Counter: {this.state.count}</h2>
        <div>
        <button onClick={this.increment}>+</button>
        <button onClick={this.decrement}>-</button>
        <button onClick={this.reset}>Reset</button>
        </div>
        <button onClick={this.toggleTheme}>Toggle Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Counter with maximum and minimum limits.

Let’s Try →

Inferno Counter with Auto Increment

import { render, Component } from 'inferno';

class Counter extends Component {
    state = { count: 0, isDark: false, auto: false, timer: null };

    increment = () => this.setState({ count: this.state.count + 1 });
    decrement = () => this.setState({ count: this.state.count - 1 });
    reset = () => this.setState({ count: 0 });
    toggleTheme = () => this.setState({ isDark: !this.state.isDark });
    toggleAuto = () => {
        if (!this.state.auto) {
        const timer = setInterval(this.increment, 1000);
        this.setState({ auto: true, timer });
        } else {
        clearInterval(this.state.timer);
        this.setState({ auto: false, timer: null });
        }
    };

    render() {
        return (
        <div className={this.state.isDark ? 'dark-theme' : 'light-theme'}>
        <h2>Counter: {this.state.count}</h2>
        <div>
        <button onClick={this.increment}>+</button>
        <button onClick={this.decrement}>-</button>
        <button onClick={this.reset}>Reset</button>
        <button onClick={this.toggleAuto}>{this.state.auto ? 'Stop Auto' : 'Start Auto'}</button>
        </div>
        <button onClick={this.toggleTheme}>Toggle Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Counter that automatically increments every second.

Let’s Try →

Inferno Counter with Double Increment

import { render, Component } from 'inferno';

class Counter extends Component {
    state = { count: 0, isDark: false };

    increment = () => this.setState({ count: this.state.count + 1 });
    doubleIncrement = () => this.setState({ count: this.state.count + 2 });
    decrement = () => this.setState({ count: this.state.count - 1 });
    reset = () => this.setState({ count: 0 });
    toggleTheme = () => this.setState({ isDark: !this.state.isDark });

    render() {
        return (
        <div className={this.state.isDark ? 'dark-theme' : 'light-theme'}>
        <h2>Counter: {this.state.count}</h2>
        <div>
        <button onClick={this.increment}>+</button>
        <button onClick={this.doubleIncrement}>++</button>
        <button onClick={this.decrement}>-</button>
        <button onClick={this.reset}>Reset</button>
        </div>
        <button onClick={this.toggleTheme}>Toggle Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Counter increments by 2 with a special button.

Let’s Try →

Inferno Counter with Even/Odd Indicator

import { render, Component } from 'inferno';

class Counter extends Component {
    state = { count: 0, isDark: false };

    increment = () => this.setState({ count: this.state.count + 1 });
    decrement = () => this.setState({ count: this.state.count - 1 });
    reset = () => this.setState({ count: 0 });
    toggleTheme = () => this.setState({ isDark: !this.state.isDark });

    render() {
        return (
        <div className={this.state.isDark ? 'dark-theme' : 'light-theme'}>
        <h2>Counter: {this.state.count} ({this.state.count % 2 === 0 ? 'Even' : 'Odd'})</h2>
        <div>
        <button onClick={this.increment}>+</button>
        <button onClick={this.decrement}>-</button>
        <button onClick={this.reset}>Reset</button>
        </div>
        <button onClick={this.toggleTheme}>Toggle Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Shows whether the current count is even or odd.

Let’s Try →

Inferno Counter with LocalStorage

import { render, Component } from 'inferno';

class Counter extends Component {
    state = { count: parseInt(localStorage.getItem('count') || 0), isDark: false };

    increment = () => { const count = this.state.count + 1; localStorage.setItem('count', count); this.setState({ count }); };
    decrement = () => { const count = this.state.count - 1; localStorage.setItem('count', count); this.setState({ count }); };
    reset = () => { localStorage.setItem('count', 0); this.setState({ count: 0 }); };
    toggleTheme = () => this.setState({ isDark: !this.state.isDark });

    render() {
        return (
        <div className={this.state.isDark ? 'dark-theme' : 'light-theme'}>
        <h2>Counter: {this.state.count}</h2>
        <div>
        <button onClick={this.increment}>+</button>
        <button onClick={this.decrement}>-</button>
        <button onClick={this.reset}>Reset</button>
        </div>
        <button onClick={this.toggleTheme}>Toggle Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Persists counter value in localStorage.

Let’s Try →

Inferno Counter with Color Themes

import { render, Component } from 'inferno';

const themes = ['light-theme','dark-theme','blue-theme'];

class Counter extends Component {
    state = { count: 0, current: 0, theme: themes[0] };

    increment = () => this.setState({ count: this.state.count + 1 });
    decrement = () => this.setState({ count: this.state.count - 1 });
    reset = () => this.setState({ count: 0 });
    toggleTheme = () => { const next = (this.state.current + 1) % themes.length; this.setState({ current: next, theme: themes[next] }); };

    render() {
        return (
        <div className={this.state.theme}>
        <h2>Counter: {this.state.count}</h2>
        <div>
        <button onClick={this.increment}>+</button>
        <button onClick={this.decrement}>-</button>
        <button onClick={this.reset}>Reset</button>
        </div>
        <button onClick={this.toggleTheme}>Switch Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Cycles through multiple color themes.

Let’s Try →

Frequently Asked Questions about Inferno

What is Inferno?

What are the primary use cases for Inferno?

High-performance SPAs. Real-time dashboards and charts. Embedded widgets with small footprint. React-compatible environments needing speed. Apps requiring extremely fast client-side rendering

What are the strengths of Inferno?

One of the fastest UI libraries available. Very small and lightweight. Easy migration from React. Great SSR performance. Stable API with minimal overhead

What are the limitations of Inferno?

Smaller ecosystem than React/Vue. Some advanced React features not supported. Less community activity. Fewer tutorials and third-party libraries. Maintenance pace slower than big frameworks

How can I practice Inferno typing speed?

CodeSpeedTest offers 8+ real Inferno code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.

Learn Other Programming Languages

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Code Sample Descriptions

Inferno Simple Counter

import { render, Component } from 'inferno';

class Counter extends Component {
    state = { count: 0, isDark: false };

    increment = () => this.setState({ count: this.state.count + 1 });
    decrement = () => this.setState({ count: this.state.count - 1 });
    reset = () => this.setState({ count: 0 });
    toggleTheme = () => this.setState({ isDark: !this.state.isDark });

    render() {
        return (
        <div className={this.state.isDark ? 'dark-theme' : 'light-theme'}>
        <h2>Counter: {this.state.count}</h2>
        <div>
        <button onClick={this.increment}>+</button>
        <button onClick={this.decrement}>-</button>
        <button onClick={this.reset}>Reset</button>
        </div>
        <button onClick={this.toggleTheme}>Switch to {this.state.isDark ? 'Light' : 'Dark'} Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Basic counter with increment, decrement, reset, and theme toggle.

Let’s Try →

Inferno Counter with Step

import { render, Component } from 'inferno';

class Counter extends Component {
    state = { count: 0, step: 5, isDark: false };

    increment = () => this.setState({ count: this.state.count + this.state.step });
    decrement = () => this.setState({ count: this.state.count - this.state.step });
    reset = () => this.setState({ count: 0 });
    toggleTheme = () => this.setState({ isDark: !this.state.isDark });

    render() {
        return (
        <div className={this.state.isDark ? 'dark-theme' : 'light-theme'}>
        <h2>Counter: {this.state.count}</h2>
        <div>
        <button onClick={this.increment}>+{this.state.step}</button>
        <button onClick={this.decrement}>-{this.state.step}</button>
        <button onClick={this.reset}>Reset</button>
        </div>
        <button onClick={this.toggleTheme}>Switch Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Counter increments/decrements by a custom step value.

Let’s Try →

Inferno Counter with Min/Max

import { render, Component } from 'inferno';

class Counter extends Component {
    state = { count: 0, min: 0, max: 10, isDark: false };

    increment = () => this.setState({ count: Math.min(this.state.count + 1, this.state.max) });
    decrement = () => this.setState({ count: Math.max(this.state.count - 1, this.state.min) });
    reset = () => this.setState({ count: 0 });
    toggleTheme = () => this.setState({ isDark: !this.state.isDark });

    render() {
        return (
        <div className={this.state.isDark ? 'dark-theme' : 'light-theme'}>
        <h2>Counter: {this.state.count}</h2>
        <div>
        <button onClick={this.increment}>+</button>
        <button onClick={this.decrement}>-</button>
        <button onClick={this.reset}>Reset</button>
        </div>
        <button onClick={this.toggleTheme}>Toggle Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Counter with maximum and minimum limits.

Let’s Try →

Inferno Counter with Auto Increment

import { render, Component } from 'inferno';

class Counter extends Component {
    state = { count: 0, isDark: false, auto: false, timer: null };

    increment = () => this.setState({ count: this.state.count + 1 });
    decrement = () => this.setState({ count: this.state.count - 1 });
    reset = () => this.setState({ count: 0 });
    toggleTheme = () => this.setState({ isDark: !this.state.isDark });
    toggleAuto = () => {
        if (!this.state.auto) {
        const timer = setInterval(this.increment, 1000);
        this.setState({ auto: true, timer });
        } else {
        clearInterval(this.state.timer);
        this.setState({ auto: false, timer: null });
        }
    };

    render() {
        return (
        <div className={this.state.isDark ? 'dark-theme' : 'light-theme'}>
        <h2>Counter: {this.state.count}</h2>
        <div>
        <button onClick={this.increment}>+</button>
        <button onClick={this.decrement}>-</button>
        <button onClick={this.reset}>Reset</button>
        <button onClick={this.toggleAuto}>{this.state.auto ? 'Stop Auto' : 'Start Auto'}</button>
        </div>
        <button onClick={this.toggleTheme}>Toggle Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Counter that automatically increments every second.

Let’s Try →

Inferno Counter with Double Increment

import { render, Component } from 'inferno';

class Counter extends Component {
    state = { count: 0, isDark: false };

    increment = () => this.setState({ count: this.state.count + 1 });
    doubleIncrement = () => this.setState({ count: this.state.count + 2 });
    decrement = () => this.setState({ count: this.state.count - 1 });
    reset = () => this.setState({ count: 0 });
    toggleTheme = () => this.setState({ isDark: !this.state.isDark });

    render() {
        return (
        <div className={this.state.isDark ? 'dark-theme' : 'light-theme'}>
        <h2>Counter: {this.state.count}</h2>
        <div>
        <button onClick={this.increment}>+</button>
        <button onClick={this.doubleIncrement}>++</button>
        <button onClick={this.decrement}>-</button>
        <button onClick={this.reset}>Reset</button>
        </div>
        <button onClick={this.toggleTheme}>Toggle Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Counter increments by 2 with a special button.

Let’s Try →

Inferno Counter with Even/Odd Indicator

import { render, Component } from 'inferno';

class Counter extends Component {
    state = { count: 0, isDark: false };

    increment = () => this.setState({ count: this.state.count + 1 });
    decrement = () => this.setState({ count: this.state.count - 1 });
    reset = () => this.setState({ count: 0 });
    toggleTheme = () => this.setState({ isDark: !this.state.isDark });

    render() {
        return (
        <div className={this.state.isDark ? 'dark-theme' : 'light-theme'}>
        <h2>Counter: {this.state.count} ({this.state.count % 2 === 0 ? 'Even' : 'Odd'})</h2>
        <div>
        <button onClick={this.increment}>+</button>
        <button onClick={this.decrement}>-</button>
        <button onClick={this.reset}>Reset</button>
        </div>
        <button onClick={this.toggleTheme}>Toggle Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Shows whether the current count is even or odd.

Let’s Try →

Inferno Counter with LocalStorage

import { render, Component } from 'inferno';

class Counter extends Component {
    state = { count: parseInt(localStorage.getItem('count') || 0), isDark: false };

    increment = () => { const count = this.state.count + 1; localStorage.setItem('count', count); this.setState({ count }); };
    decrement = () => { const count = this.state.count - 1; localStorage.setItem('count', count); this.setState({ count }); };
    reset = () => { localStorage.setItem('count', 0); this.setState({ count: 0 }); };
    toggleTheme = () => this.setState({ isDark: !this.state.isDark });

    render() {
        return (
        <div className={this.state.isDark ? 'dark-theme' : 'light-theme'}>
        <h2>Counter: {this.state.count}</h2>
        <div>
        <button onClick={this.increment}>+</button>
        <button onClick={this.decrement}>-</button>
        <button onClick={this.reset}>Reset</button>
        </div>
        <button onClick={this.toggleTheme}>Toggle Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Persists counter value in localStorage.

Let’s Try →

Inferno Counter with Color Themes

import { render, Component } from 'inferno';

const themes = ['light-theme','dark-theme','blue-theme'];

class Counter extends Component {
    state = { count: 0, current: 0, theme: themes[0] };

    increment = () => this.setState({ count: this.state.count + 1 });
    decrement = () => this.setState({ count: this.state.count - 1 });
    reset = () => this.setState({ count: 0 });
    toggleTheme = () => { const next = (this.state.current + 1) % themes.length; this.setState({ current: next, theme: themes[next] }); };

    render() {
        return (
        <div className={this.state.theme}>
        <h2>Counter: {this.state.count}</h2>
        <div>
        <button onClick={this.increment}>+</button>
        <button onClick={this.decrement}>-</button>
        <button onClick={this.reset}>Reset</button>
        </div>
        <button onClick={this.toggleTheme}>Switch Theme</button>
        </div>
        );
    }
}

render(<Counter />, document.body);

Cycles through multiple color themes.

Let’s Try →

Frequently Asked Questions about Inferno

What is Inferno?

What are the primary use cases for Inferno?

High-performance SPAs. Real-time dashboards and charts. Embedded widgets with small footprint. React-compatible environments needing speed. Apps requiring extremely fast client-side rendering

What are the strengths of Inferno?

One of the fastest UI libraries available. Very small and lightweight. Easy migration from React. Great SSR performance. Stable API with minimal overhead

What are the limitations of Inferno?

Smaller ecosystem than React/Vue. Some advanced React features not supported. Less community activity. Fewer tutorials and third-party libraries. Maintenance pace slower than big frameworks

How can I practice Inferno typing speed?

CodeSpeedTest offers 8+ real Inferno code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.

Learn Inferno - 8 Code Examples & CST Typing Practice Test

Learn INFERNO with Real Code Examples

Explain

Core Features

Basic Concepts Overview

Project Structure

Building Workflow

Difficulty Use Cases

Comparisons

Versioning Timeline

Glossary

Installation Setup

Environment Setup

Config Files

Cli Commands

Internationalization

Accessibility

Ui Styling

State Management

Data Management

Architecture

Rendering Model

Architectural Patterns

Real World Architectures

Design Principles

Scalability Guide

Migration Guide

Performance Notes

Security Notes

Monitoring Analytics

Code Quality

Practical Examples

Troubleshooting

Testing Guide

Deployment Options

Tools Ecosystem

Integrations

Productivity Tips

Challenges

Learning Path

Skill Improvement Plan

Interview Questions

Cheat Sheet

Books

Tutorials

Official Docs

Community Links

Community Support

Monetization

Future Roadmap

When Not To Use

Final Summary

Faq

Code Sample Descriptions

Inferno Simple Counter

Inferno Counter with Step

Inferno Counter with Min/Max

Inferno Counter with Auto Increment

Inferno Counter with Double Increment

Inferno Counter with Even/Odd Indicator

Inferno Counter with LocalStorage

Inferno Counter with Color Themes

Frequently Asked Questions about Inferno

What is Inferno?

What are the primary use cases for Inferno?

What are the strengths of Inferno?

What are the limitations of Inferno?

How can I practice Inferno typing speed?

Learn Other Programming Languages

Learn Inferno - 8 Code Examples & CST Typing Practice Test

Learn INFERNO with Real Code Examples

Explain

Core Features

Basic Concepts Overview

Project Structure

Building Workflow

Difficulty Use Cases

Comparisons

Versioning Timeline

Glossary