An Error Boundary in React is a special type of component that catches JavaScript errors anywhere in its child component tree, logs those errors, and displays a fallback UI instead of crashing the whole app .

Key Points:

• It helps gracefully handle runtime errors in components.
• Only catches errors during rendering, lifecycle methods, and constructors of the components below it.
• Does not catch:
  • Errors in event handlers
  • Asynchronous code (e.g. setTimeout, Promises)
  • Server-side rendering errors
  • Errors thrown in the error boundary itself

✅ Line 1

class ErrorBoundary extends React.Component {

You're defining a class component named ErrorBoundary. It extends React.Component, meaning it inherits lifecycle methods like render, componentDidCatch, etc.

This component will act as a boundary to catch JavaScript errors in its child components.

✅ Line 2–5

constructor(props) {
  super(props);
  this.state = { hasError: false };
}

• constructor: Called when the component is created.
• super(props): Calls the parent class constructor with props, required when using this.props.
• this.state: Initializes a state variable hasError to track whether an error occurred.

✅ Line 7–9

static getDerivedStateFromError(error) {
  return { hasError: true };
}