⚛️ React DevTools Usage

⚛️ Introduction

The React Developer Tools (DevTools) are browser extensions that allow you to inspect the React component tree, view props, state, hooks, and performance metrics in real-time.

It is available for both Google Chrome and Mozilla Firefox, and integrates seamlessly into your browser’s Developer Tools panel.

? Installation

• ? Chrome: Install from Chrome Web Store
• ? Firefox: Install from Firefox Add-ons
• After installation, open your React app and check the Components and Profiler tabs in DevTools.

? Components Panel

The Components panel shows the React component tree of your app. You can click any component to inspect its:

• Props – passed data from parent components
• State – internal data managed by hooks or classes
• Hooks – active React hooks with their values
• Context – values provided via Context API

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

When you click the Counter component in DevTools, you’ll see:

• State: { count: 0 }
• Hooks: useState
• Real-time updates as you interact with the component.

⚙️ Profiler Panel

The Profiler tab helps you measure rendering performance. You can record interactions and see which components re-rendered, how long they took, and why.

1. Open the Profiler tab.
2. Click “Start profiling and reload page”.
3. Interact with your app.
4. Stop profiling and analyze render times and flame charts.

? Example: Detecting Unnecessary Re-renders

Use the Profiler to identify components re-rendering too often. In the chart, the height and color of bars indicate render duration.

// Example optimization target
function Parent({ text }) {
  return (
    <div>
      // Memoized child to prevent re-renders
      <MemoizedChild />
      <p>{text}</p>
    </div>
  );
}

const MemoizedChild = React.memo(function Child() {
  console.log("Child rendered");
  return <div>I don't change often</div>;
});

When you run the Profiler, you’ll notice MemoizedChild doesn’t re-render unless necessary — confirming memoization works.

? Live Demo: Inspect Me!

The box below is a real running React application embedded in this page. If you have React DevTools installed, you can inspect it right now!

⚡ Common Uses

• Inspect and edit component props/state live.
• Debug Context API and Hook state changes.
• Analyze component re-render patterns.
• Measure and optimize performance bottlenecks.
• Track updates across Suspense and concurrent features.