What is React virtual DOM?

React virtual DOM is a lightweight copy of the actual DOM. It is a JavaScript object that represents the actual DOM elements and their properties. React uses this virtual DOM to optimize the performance of the application by minimizing the number of changes that need to be made to the actual DOM. Instead of updating the entire DOM tree, React only updates the parts of the tree that have changed. This makes the application faster and more efficient.

When a user interacts with a React application, the virtual DOM is updated first. React then compares the updated virtual DOM with the previous version of the virtual DOM to identify the changes that have been made. Once the changes have been identified, React updates only those parts of the actual DOM that have changed. This process is called reconciliation. By using the virtual DOM, React minimizes the number of updates that need to be made to the actual DOM, which improves the performance of the application.

// Example of using React virtual DOM

import React, { useState } from 'react';

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

  function handleClick() {
    setCount(count + 1);
  }

  return (
<div>
  <h1>Count: {count}</h1>
  <button onclick="{handleClick}">Increment</button>
</div>
  );
}

In the above example, we have a simple React component that displays a count and a button. When the button is clicked, the count is incremented. React uses the virtual DOM to update the count value in the actual DOM without updating the entire DOM tree. This makes the application faster and more efficient.