What is the difference between state and props in React?

As a React developer, understanding the difference between state and props is crucial for building efficient and scalable applications. While both state and props are used to manage data in React components, they serve different purposes and have distinct characteristics.

State

State is a built-in feature of React components that allows them to keep track of and manage their internal data. It represents the current state of a component and can be updated using the setState() method. State is mutable and local to a component, meaning it can only be accessed and modified within the component itself.

Here’s an example of how state can be used in a React component:

{`
import React, { Component } from 'react';

class Counter extends Component {
  constructor(props) {
    super(props);
    this.state = {
      count: 0
    };
  }

  incrementCount() {
    this.setState({ count: this.state.count + 1 });
  }

  render() {
    return (
      

        Count: {this.state.count}
         this.incrementCount()}>Increment
      
    );
  }
}

export default Counter;
  `}

In the above example, the Counter component has an internal state property called count. The incrementCount() method is used to update the state by incrementing the count value. The current count is displayed in the render method using {this.state.count}.

Props

Props, short for properties, are used to pass data from a parent component to its child components. Unlike state, props are read-only and cannot be modified by the child component. They are passed down from the parent component and remain unchanged throughout the component’s lifecycle.

Here’s an example of how props can be used in a React component:

{`
import React from 'react';

const Greeting = (props) => {
  return (
    

      
Hello, {props.name}!
      {props.message}
    
  );
}

export default Greeting;
  `}

In the above example, the Greeting component receives two props: name and message. These props are passed down from the parent component and displayed in the render method using {props.name} and {props.message}.

Conclusion

In summary, state is used to manage internal data within a component and can be updated using setState(). Props, on the other hand, are used to pass data from a parent component to its child components and are read-only. Understanding the difference between state and props is essential for writing clean and maintainable React code.