Building Interactive Demos in MDX: Taking Your Blog Posts to the Next Level

Static code examples are great, but interactive demos can transform your blog posts from informative to truly engaging. In this guide, I'll show you how to build various types of interactive demos in your MDX blog posts, making your technical content more hands-on and educational.

Why Interactive Demos Matter

Interactive demos offer several key benefits:

• Better Engagement: Readers can experiment with code directly in your blog post
• Hands-on Learning: Visual understanding through interaction beats reading alone
• Reduced Context Switching: No need to open a separate CodeSandbox or IDE
• Immediate Feedback: See results instantly as you modify code
• Better Retention: Active learning leads to better understanding

Prerequisites

This guide builds on the MDX blog setup covered in How I built my Blog with MDX, Next.js, and Tailwind CSS. Make sure you have:

• A Next.js blog with MDX support (using next-mdx-remote)
• React components set up for MDX
• Tailwind CSS for styling

Setting Up Interactive Components in MDX

The key to interactive demos in MDX is creating client components (components that use React hooks and browser APIs) and registering them in your MDX component map.

Understanding Client vs Server Components

Since we're using next-mdx-remote with the App Router, we need to mark interactive components with "use client" to enable React hooks and browser APIs.

Component Organization

I organize my interactive demo components in src/components/mdx/:

src/components/mdx/
├── LivePreview.tsx          # Live code preview component
├── CodePlayground.tsx       # Interactive code editor
├── InteractiveDemo.tsx      # Generic wrapper for demos
├── ComparisonDemo.tsx       # Side-by-side comparisons
├── StepByStepDemo.tsx       # Progressive disclosure
└── demos/
    ├── CounterDemo.tsx      # Example: Counter component
    ├── FormValidationDemo.tsx
    ├── ApiSimulatorDemo.tsx
    └── AnimationDemo.tsx

Interactive Demo Types

Let's explore the different types of interactive demos you can build:

1. Live Code Preview

The LivePreview component displays code alongside a live React component preview. Perfect for demonstrating React components, hooks, and patterns.

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

Here's how to use it in your MDX:

<LivePreview
	code={`const MyComponent = () => {
      return <div>Hello World</div>;
    };`}
	preview={<MyComponent />}
	title="My Demo"
	description="This is what it does"
/>

2. Interactive Demo Wrapper

The InteractiveDemo component is a simple wrapper for any interactive content. Use it to create consistent, styled containers for your demos.

Usage:

<InteractiveDemo title="Demo Title" description="What this demo shows">
	<YourComponent />
</InteractiveDemo>

4. Comparison Demos

Use ComparisonDemo to show side-by-side comparisons of different approaches, before/after states, or different implementations.

class MyComponent extends React.Component {
  render() {
    return <div>Hello</div>;
  }
}

const MyComponent = () => {
  return <div>Hello</div>;
};

5. Step-by-Step Demos

The StepByStepDemo component is perfect for progressive disclosure, walking readers through complex processes step by step.

import { useState } from 'react';

Practical Examples

Let's look at some real-world examples you can use in your blog posts:

Example 1: Form Validation Demo

Perfect for demonstrating form validation patterns, error handling, and user feedback.

This demo shows:

• Real-time validation feedback
• Multiple validation rules
• Error state management
• User-friendly error messages

Example 2: API Call Simulator

Demonstrate loading states, error handling, and async operations.

Key features demonstrated:

• Loading states
• Success handling
• Error handling
• Async/await patterns

Example 3: Animation Demo

Show CSS animations, transitions, and interactive controls.

This demonstrates:

• CSS animations
• Interactive controls
• State-driven animations
• User-controlled playback

Implementation Details

Component Architecture

Each interactive component follows a consistent structure:

"use client";
 
import { useState } from "react";
 
export function MyDemo() {
	const [state, setState] = useState(initialValue);
 
	return <div className="styled-container">{/* Interactive content */}</div>;
}

Key points:

• Always use "use client" directive
• Use React hooks for interactivity
• Style with Tailwind CSS classes
• Support dark mode with theme-aware classes

Styling with Tailwind CSS

All components use Tailwind's theme-aware classes for consistent styling:

// Background colors adapt to theme
className = "bg-background text-foreground";
 
// Borders use theme colors
className = "border-border";
 
// Muted colors for secondary content
className = "text-muted-foreground bg-muted";

State Management in Demos

For simple demos, local state with useState is sufficient:

const [count, setCount] = useState(0);

For more complex demos, you might use:

• useReducer for complex state logic
• Context API for shared state between demos
• Custom hooks for reusable logic

Registering Components in MDX

To use these components in your MDX files, register them in your MDX components map:

// src/components/mdx/mdx.tsx
import { LivePreview } from "./LivePreview";
import { InteractiveDemo } from "./InteractiveDemo";
import { CounterDemo } from "./demos/CounterDemo";
// ... other imports
 
let components = {
	// ... existing components
	LivePreview,
	InteractiveDemo,
	CounterDemo,
	// ... other demo components
};
 
export function CustomMDX(props: MDXRemoteProps) {
	return (
		<MDXRemote
			{...props}
			components={{ ...components, ...(props.components || {}) }}
		/>
	);
}

Advanced Techniques

Lazy Loading Demos

For performance, you can lazy load heavy demo components:

import dynamic from "next/dynamic";
 
const HeavyDemo = dynamic(() => import("./demos/HeavyDemo"), {
	loading: () => <p>Loading demo...</p>,
});

Example used in this post:

import { LazyAnimationDemo } from "@/components/mdx/LazyAnimationDemo";
 
<LazyAnimationDemo />;

Embedding External Tools

You can also embed external code playgrounds:

// CodeSandbox embed
<iframe
	src="https://codesandbox.io/embed/..."
	style={{ width: "100%", height: "500px" }}
	title="CodeSandbox demo"
/>

Example used in this post (iframe stays sandboxed and does not execute in your page context):

Best Practices

When to Use Interactive Demos

Use interactive demos when:

• ✅ Demonstrating concepts that benefit from experimentation
• ✅ Showing before/after comparisons
• ✅ Teaching through hands-on examples
• ✅ Making complex topics more accessible

Avoid when:

• ❌ Simple code snippets are sufficient
• ❌ The demo would significantly slow page load
• ❌ The concept doesn't benefit from interaction

Performance Considerations

• Lazy load heavy demos
• Code split large demo components
• Optimize images and assets in demos
• Monitor bundle size impact

Mobile Responsiveness

Ensure all demos work well on mobile:

• Use responsive Tailwind classes
• Test touch interactions
• Consider mobile-first layouts
• Provide fallbacks for mobile limitations

Accessibility

Make demos accessible:

• Use semantic HTML
• Add ARIA labels where needed
• Ensure keyboard navigation works
• Test with screen readers
• Provide text alternatives

Troubleshooting

Component Not Rendering

If a component doesn't render in MDX:

1. Check the "use client" directive: Client components need this
2. Verify component registration: Ensure it's in the components map
3. Check imports: Make sure all dependencies are imported
4. Review console errors: Check browser console for errors

Styling Issues

If styles aren't applying:

1. Check Tailwind classes: Ensure classes are valid
2. Verify theme variables: Use theme-aware color classes
3. Check CSS specificity: May need !important in rare cases
4. Review dark mode: Test both light and dark themes

State Not Updating

If state isn't updating:

1. Verify "use client": Required for hooks
2. Check event handlers: Ensure they're properly bound
3. Review state updates: Use functional updates if needed
4. Check for re-renders: Component might be unmounting

Conclusion

Interactive demos can transform your technical blog posts from static documentation into engaging, hands-on learning experiences. By combining MDX's flexibility with React's interactivity, you can create content that:

• Engages readers more effectively
• Improves learning outcomes
• Reduces context switching
• Makes complex topics accessible

Start with simple demos and gradually add more complex interactions as you become comfortable with the patterns. The components we've built provide a solid foundation, but don't hesitate to customize them for your specific needs.

Remember: the best demos are those that make learning easier and more enjoyable. Experiment, iterate, and have fun building interactive content!

Resources

• MDX Documentation
• Next.js App Router
• React Hooks Documentation
• Tailwind CSS

Want to see the source code? Check out the GitHub repository for this blog.