Time is a valuable asset that no user would like to waste, especially when using a web application. React, a popular JavaScript library, is known for its rendering performance and is used by big names such as LinkedIn, Netflix, CSDN, Airbnb, and DropBox for their web applications.

React.js is a popular language that uses clever techniques to minimize the number of costly DOM operations required to update the UI. For many applications, using React can lead to a fast user interface without the need for specific performance optimization. However, there are several tips and best practices for React.js that can help boost your application’s performance.

1. Lazy loading Images in React

If your React application has numerous images, it may negatively affect its performance. This happens because the browser must load all images in the DOM before displaying the user interface. To prevent this issue, it is recommended to use lazy loading for images. This approach only renders the image when it is about to appear on the user’s screen, instead of loading all images at once. This method helps to minimize the creation of unnecessary DOM nodes.

To implement lazy loading, two popular libraries that can be used are react-lazy-load and react-lazy-load-image-component, both of which can help improve a React app’s performance.

2. Key Coordination for List Rendering

When working with lists in React, assigning key attributes to each element is crucial to facilitate the rendering of upcoming list items.

Incorrectly assigned component keys for dynamic lists can not only be unhelpful for the user but also hinder the performance of a React app. This is because new list entries may unnecessarily suggest previous list entries.

To avoid this bottleneck, assigning a unique key value to each list component is important. Using the Key={} attribute for dynamic lists can significantly improve the performance of your React app.

3. Windowing or List Virtualization in React Applications

React applications that display long lists can often encounter performance issues. When the app loads, the entire list is rendered in the DOM, causing a delay in the user interface and significantly impacting the React.js app’s performance.

To overcome this bottleneck, List Virtualization or Windowing can be utilized. This approach restricts the number of items that are rendered on the DOM and visible on the app screen, rather than displaying the complete long list of components.

Two popular libraries available for implementing windowing in React are react-window and react-virtualized. By rendering only a small subset of the extensive list on the app screen, the performance of your React app can be improved.

4. Understand How to Handle ‘this’

Functional components in React do not require the use of ‘this’ binding, making them a preferable option whenever possible. However, if you are using ES6 binding, React will not automatically bind your functions within components. In such cases, manual binding can be achieved using several methods, including:

  • Bind in render
  • Allow arrow function in render
  • Bind in the constructor
  • Bind arrow function in the class property [Not in official ECMAScript]

5. Functional Components & Component Interaction

One effective way to optimize the performance of React applications is by using functional components. Although it may seem like a common tactic, it is a simple and proven approach to quickly develop efficient and high-performance React applications.

Our React experts have some advice when using Components.

Some advantages of using Advanced React component patterns like React Devtools (extension) are

  • Require less code
  • Easy to understand
  • Components are stateless
  • Easy to test
  • Flexibility to extract smaller components
  • Intractability

6. Use a Function in ‘setState’

Using a function instead of an object in the setState function in React is recommended. This is because state changes are not immediately implied, as explained in React documentation. Rather than using the following syntax::

this.setState({correctData: !this.state.correctData});

Use this way:

this.setState((prevState, props) => {

return {correctData: !prevState.correctData});

}

This function receives the previous state as its first argument and the props at the time the update is applied as the second argument.

7. Utilize Prop-Types

The Prop-types library can be used for type checking of props in React. To import the function from the prop-type library, you can use the following code snippet:

import PropTypes from ‘prop-types’;

class Welcome extends Component {

render() {

return <h1>Hello, {this.props.name}</h1>;

 }

}

Welcome.propTypes = {

name: PropTypes.string.isRequired

}

8. Server-Side Rendering (SSR)

It’s essential to use SSR consciously and determine whether you need SEO or not for your application. SSR can cause a significant load, so it’s best to avoid using it unnecessarily.

9. Trim JavaScript Bundles

Trimming JavaScript bundles can significantly improve the performance of your React app by reducing code redundancy. Eliminating duplicates and unnecessary code can improve your app’s performance. Therefore, it is important to analyze and determine which code can be bundled to optimize the performance of your React app.

10. React Redux Optimization Tips

When building React apps with Redux toolkit, performance issues can arise. Yahoo faced a similar problem, but it was overcome by using the RESELECT library when allocating higher-order components for rendering operations. This library proved to be very effective.

Another way to optimize React Redux app performance is to use Immutable.js. Immutable lists outperformed mutable lists, with the performance up to four times better. When mutable data structures are used in a Redux app, the Redux state tree requires a lot of memory to copy data, which can negatively impact the app’s performance.

11. Improve React App Performance Using React Memo [Memoization]

Here, we will provide a brief overview of how to use React memo to optimize the performance of React applications.

React memo is a higher-order component that can provide a performance boost in certain cases by memoizing the result of a component’s render method. If a component produces the same output when given the same props, you can wrap it in React.memo. This will cause React to reuse the last rendered result instead of rendering the component again.

It is important to note that React.memo only checks for changes in props. If a function component wrapped in React.memo uses state or context from useState, useReducer, or useContext, it will still be rerendered when there are changes to that state or context.

By default, React.memo will only perform a shallow comparison of complex objects in the props object. However, you can provide a custom comparison function as the second argument to have more control over the comparison.

Here is an example of how to use React.memo with a custom comparison function:

function MyComponent(props) {

/* render using props */

}

function areEqual(prevProps, nextProps) {

/*

return true if passing nextProps to render would return

the same result as passing prevProps to render,

otherwise return false

*/

}

export default React.memo(MyComponent, areEqual);

It is important to remember that using React.memo is only intended as a performance optimization and should not be relied on to prevent renders. Depending on it to prevent renders can lead to bugs in your application.

12. Using Immutable Data Structures

Data immutability is not a specific architecture or design pattern, but rather a coding practice that encourages a strict unidirectional data flow. This approach, which originates from functional programming, can be applied to the design of front-end app and offers several benefits:

  • Zero side effects.
  • Immutable data objects are simpler to create, test, and use.
  • Helps prevent temporal coupling.
  • Easier to track changes.

In React, components are used to maintain the internal state of the application, and changes to the state can trigger a component re-render. React builds and maintains an internal representation of the UI, known as the Virtual DOM. When a component’s props or state changes, React compares the newly returned element with the previously rendered one. If the two elements are not equal, React updates the DOM. It is crucial to be cautious when modifying the state to avoid unintended effects.

React state should be treated as immutable. We should never mutatethis.statedirectly, as callingsetState()afterward may replace the mutation you made.

Conclusion

After gaining a better understanding of React performance issues and optimization techniques, we encourage you to implement the tips we’ve shared in this blog to improve the performance of your React application. You can take your app to new heights by working with a trusted ReactJS Development Company that has the expertise and experience to optimize your app’s performance.