React 18’s Automatic Batching: Improving Performance and Simplifying State Updates

React 18 introduces a new feature called automatic batching, which significantly improves the performance of React applications. In this article, we will take a closer look at what automatic batching is, how it works, and the benefits it offers to developers.

Automatic batching is a new feature in React 18 that groups multiple state updates into a single batch, reducing the number of renders that occur when a user interacts with the application. In previous versions of React, every state update would trigger a render, which could result in unnecessary re-renders and slow down the application’s performance.

With automatic batching, React tracks all state updates that occur within a single browser event loop iteration and groups them into a single batch. The batch is then processed together, reducing the number of renders that need to be performed by the browser.

Automatic batching works by delaying the rendering of updates until the end of the browser event loop iteration. When a state update occurs, React will not immediately trigger a render. Instead, it will add the update to a batch and wait for any other updates that occur during the same event loop iteration.

Once all updates for the current iteration have been collected, React will process them together in a single batch. This reduces the number of renders that need to be performed by the browser, resulting in faster and smoother user experiences.

Benefits of Automatic Batching

There are several benefits to using automatic batching in React applications. These include:

1. Improved Performance: Automatic batching significantly improves the performance of React applications by reducing the number of renders that occur when a user interacts with the application. This results in faster and smoother user experiences.
2. Reduced CPU Usage: By grouping updates into a single batch, automatic batching reduces the amount of work that needs to be done by the CPU, resulting in lower CPU usage and better overall performance.
3. Simplified Code: Automatic batching simplifies the code needed to manage state updates in React applications. Developers no longer need to worry about managing state updates manually or optimizing for performance, as React takes care of this automatically.

Updating State with Multiple SetState Calls

import { useState } from 'react';

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

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

  return (
    <div>
      <p>Count: {count}</p>
      <button onClick={handleClick}>Increment Count</button>
    </div>
  );
}

In this example, we have a simple React component that renders a counter and a button. When the button is clicked, the handleClick function is called, which updates the count state using two setCount calls.

In previous versions of React, these two setCount calls would have triggered two separate renders, resulting in unnecessary re-renders and potentially slower performance. However, with automatic batching in React 18, these two setCount calls are grouped into a single batch and processed together, resulting in only one render and better performance.

Updating State in a Loop

import { useState } from 'react';

function App() {
  const [items, setItems] = useState([]);

  function handleClick() {
    for (let i = 0; i < 3; i++) {
      setItems(prevItems => [...prevItems, `Item ${i}`]);
    }
  }

  return (
    <div>
      <ul>
        {items.map(item => (
          <li key={item}>{item}</li>
        ))}
      </ul>
      <button onClick={handleClick}>Add Items</button>
    </div>
  );
}

In this example, we have a React component that renders a list of items and a button. When the button is clicked, the handleClick function is called, which updates the items state in a loop using the setItems call.

In previous versions of React, this would have triggered multiple renders for each iteration of the loop, resulting in slower performance. However, with automatic batching in React 18, these multiple setItems calls are grouped into a single batch and processed together, resulting in only one render and better performance.

Automatic batching is a powerful new feature in React 18 that offers significant benefits to developers. By reducing the number of renders that occur when a user interacts with the application, automatic batching improves performance, reduces CPU usage, and simplifies code. If you are building a React application, be sure to take advantage of automatic batching to improve the user experience and overall performance of your application.