6. React js State Vs Props where to use what

📝 React Blog: Understanding State and Props with Examples

🔹 What are Props in React?

Props (short for properties) are used to pass data from parent components to child components. They are read-only, meaning a component cannot change the props it receives.

✅ Props Example

const App = () => {
  return (
    <div>
      <h1>Props Example</h1>
      <Greeting name="Anjum" />
    </div>
  );
};

const Greeting = ({ name }) => {
  return <h2>Hello, {name}!</h2>;
};

Explanation:
The App component passes name="Anjum" to Greeting.
Greeting receives name via props and displays “Hello, Anjum!”.

🔹 What is State in React?

State is a built-in object that allows components to track changes over time. Unlike props, state is mutable and local to the component.

✅ State Example

import React, { useState } from 'react';

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

  return (
    <div>
      <h1>State Example</h1>
      <p>You clicked {count} times</p>
      <button onClick={() => setCount(count + 1)}>
        Click Me
      </button>
    </div>
  );
};

export default Counter;

Explanation:
useState(0) initializes count to 0.
When the button is clicked, setCount updates the state, re-rendering the component.

🔁 Props + State Combined Example

const App = () => {
  return (
    <div>
      <h1>Combined Example</h1>
      <User name="Aisha" />
    </div>
  );
};

const User = ({ name }) => {
  const [likes, setLikes] = React.useState(0);

  return (
    <div>
      <h2>Hello, {name}</h2>
      <p>{name} has {likes} likes</p>
      <button onClick={() => setLikes(likes + 1)}>
        Like
      </button>
    </div>
  );
};

Takeaways:
App passes name="Aisha" via props.
User uses useState to track likes. Each click increases likes for Aisha.

🧠 Conclusion