The Best Optimization Techniques in React

Q: How does list virtualization benefit React apps?

List virtualization, achieved through windowing frameworks like React-Window and React-Virtualized, improves app performance by displaying only a portion of data simultaneously rather than all at once.

Q: What is the purpose of using React.Fragment?

React.Fragment allows grouping elements without adding extra nodes to the DOM, improving code cleanliness and performance.

Q: How does lazy loading with React.Suspense enhances app performance?

Lazy loading and React.Suspense improves performance by loading only the necessary code, providing a better user experience by displaying loading indicators while components load.

Q: Why should developers use the production build of React?

The production build offers optimized performance compared to the development build, reducing bulkiness and improving speed.

Q: How does React handle 'this' in functional components?

‘This' binding in functional components can be managed through various methods such as render binding, constructor binding, arrow functions, or binding arrow functions in class properties, ensuring optimal performance and behaviour.

# React # Javascript

Pravin Prajapati · 24 Apr 2024

Why do CSDN, Dropbox, LinkedIn, and other large companies use React for their website design? Some might say it's a popular tool, but there's more to it than that. We are talking about the advantages it provides.

One significant advantage is that React helps you build your website or app faster than other tools. This means you can save significant time, which every firm values.

Let us discuss optimising your website's performance and show you how our ReactJS development team can help. Let's get started right now!

How React's UI Update System Works

Let's start by understanding how React updates its user interface (UI) and how to measure app performance before we get into the best ways to make React apps faster.

If you've been using React or starting out, you've probably heard of the term 'Virtual DOM', right?

So, what exactly is the Virtual DOM, and why does React use it?

The VirtualDOM is a clever programming concept. It's like storing an imaginary version of your website's UI in memory. React uses ReactDOM to keep this Virtual DOM in sync with the one on the webpage.

Creating a component in React creates a Virtual DOM for the component's portion of the webpage. Every time the component's state changes, React updates this Virtual DOM and compares it to the previous version. Then, it determines what has changed and only updates the relevant parts of the actual DOM. This process is known as 'diffing', allowing React to update the webpage more efficiently.

Performance Optimization Techniques for React

Optimization is always essential to understand the platform's hassle and make it easy to find the factors that prevent your platform from running smoothly. But before making any changes here, we provide some tips that can be directly implemented in your React and make it run smoothly.

1. List Virtualization in React Apps

When your app displays a large amount of data, you should use a feature known as 'windowing'. This method makes your app run faster by only showing a small portion of the data at a time rather than all at once.

Two windowing frameworks are available: React-Window and React-Virtualized. They come with ready-to-use components for lists, grids, and tables. If you need something unique for your app, like Twitter did, you can create your own windowing part.

2. Use React.Fragment to avoid adding extra nodes to the DOM

React fragments are a convenient way to avoid extra divs cluttering your code. They don't add any additional elements to the browser, so your content will appear without any extra wrappers.

React may require you to display a collection of related items or many elements. Want to see an example? Let's look at the illustration.

function App() {
return(
<div>
        <h1>Hello ELightwalk! </h1>
        <h1>Hello ELightwalk Again! </h1>
</div>
);
}

If you do not wrap adjacent JSX elements inside a parent tag, you will receive an error message stating, "Adjacent JSX elements must be wrapped in an enclosing tag." So, you'll have to put both elements inside a parent <div>.

Although this fix works well, it adds another node to the DOM, which can cause issues if a child component is wrapped inside a parent component.

React Fragment is an excellent solution for avoiding the addition of an extra node. This method allows you to group elements without adding anything to the DOM.

Function Columns ()
{
Return (
<React.Fragment>
<td> Hello ELightwalk! </td>
<td> Hello ELightwalk Again! </td>
<React.Fragment>
);
}

3. Try React.Suspense and React.Lazy for Lazy Loading Elements

It's often said, "Never load more code than is necessary for your users."

Why is that? Giving your users extra code they don't need can slow down your app's performance.

Now let's look at why Lazy Load works so well.

Things can get big quickly in a React app. You might have many components, each with 10 to 500 lines of code.

If you load every component, even those the user does not need right away, your app will slow down and become less enjoyable. Lazy loading helps with this by only loading the required code.

Load component without Lazy Load

import React from 'react';
import GalleryComponent from './GalleryComponent'

const HomeComponent = () => (
<div>
<GalleryComponent />
</div>
)

Load component with Lazy Load

import React, { lazy } from 'react';
const GalleryComponent = lazy(() => import('./GalleryComponent'));

const HomeComponent = () => (
<div>
<GalleryComponent />
</div>
)

Now that you've seen how useful Lazy Loading can be let's examine how it can be combined with Suspense.

You may wonder why we need both Lazy Load and Suspense. To better understand this, let us consider an example similar to what we have already discussed.

Consider a component called <GalleryComponent />. This component may suffer from slow API requests, low-power devices, poor network connections, or the need to load large amounts of JavaScript.

import React, { lazy } from 'react';

/*
- GalleryComponent contain API request / large JavaScript payload.
*/
const GalleryComponent = lazy(() => import('./GalleryComponent'));

const HomeComponent = () => (
<div>
<GalleryComponent />
</div>
)

As users may see a blank space while waiting for <GalleryComponent/> to load, depending only on lazy loading may lead to a bad user experience. That's where React Suspension comes in.

React Suspense does an excellent job of showing users a loading message or component while the main component loads. This way, users are informed about the loading process rather than staring at a blank screen.

import React, { lazy, Suspense } from 'react';

const GalleryComponent = lazy(() => import('./GalleryComponent'));

const renderLoader = () => <p>Loading...</p>;

const DetailsComponent = () => (
<Suspense fallback={renderLoader()}>
<GalleryComponent />
</Suspense>
)

Suspense allows you to specify a fallback component displayed to users while the main component loads. Users will notice a "loading..." message or other alert while <GalleryComponent /> loads. This improves the user experience by providing feedback while loading.

4. Use the Production Build

When testing the performance of your React apps, you must always use the minified version of the production build. React provides helpful warnings, particularly during development. However, these warnings can cause React to slow down and become bulkier. Therefore, when deploying your project, you should use the production version.

If you need to figure out how your build process is configured, you can verify with React Developer Tools for Chrome. A website that uses React in production mode will have a dark background icon. However, it will have a red background when in development mode.

You can use React in development mode while working on it. However, when you release your app to users, switch to production mode.

Note: If using React via CDN, update it from development files to production-ready ones.

5. Understand the Handling of ‘THIS’

Understanding how this works is another key to optimizing React performance.

You don't have to worry about this binding as much as you do with classes when using functional components. React does not automatically bind functions within functional components, but you can do it manually if necessary. Here are some strategies for dealing with it:

Render binding: Bind the function directly in the render method.
Constructor binding: Bind the function in the component's constructor.
Arrow function in render: Define the function as an arrow function directly in the render method.
Bind arrow function in the class property: Define the function as an arrow function in the class property and bind it there.

These methods ensure this behaves correctly within your component functions, maximising performance and avoiding potential problems.

6. Dependency optimization

When optimising the size of your application bundle, consider how much code you're using from your dependencies.

For example, if you're using Moment.js, which includes localised files for multilingual support but only needs one language, you can reduce the size of your bundle by deleting the unused locales. Tools such as the moment-locales-webpack-plugin can help you achieve this.

Similarly, you may only use a portion with libraries like Lodash, which provides many functions. Additional methods in your final bundle could be more efficient in such cases. Tools such as lodash-webpack-plugin can help you remove unused functions and reduce the size of your bundle.

You can use this optimisation technique on various dependencies to ensure your final bundle has only the code you require, which will minimise load times and increase performance.

7. Spreading props to DOM elements

Spreading props on DOM elements, like in the first example, can add unknown HTML attributes, which is considered an unnecessary and harmful practice.

const CommentsText = props => {
    return (
      <div {...props}>
        {props.text}
      </div>
    );
  };

Instead, it's better to set specific attributes, as shown in the second example. This ensures clarity and avoids adding unnecessary attributes to your DOM elements.

const CommentsText = props => {
    return (
      <div specificAttr={props.specificAttr}>
        {props.text}
      </div>
    );
};

8. Important Coordination when Rendering Lists

When working with lists in React, key attributes must be assigned to elements. These keys help React render the list items more efficiently.

If you mistakenly assign the same key to multiple list elements in dynamic lists, your React app can experience user issues and performance bottlenecks. In these cases, the new list entry may accidentally suggest the previous one, which is unnecessary and confusing.

To solve this problem and improve the performance of your React app, ensure that each list component has a distinct key value. You can accomplish this by incorporating the key attributes into your dynamic lists. Thanks to this, React can smoothly handle and update the list of items without confusion or performance problems.

Essence

You now understand the various React optimisation approaches. You can improve the performance of your React applications by using the top 8 approaches described in this article.

If you have trouble implementing these techniques, consider contacting professionals at a reputable React Development Company like Elightwalk. Our experts can help you implement these strategies. We specialise in analysing and optimising rendering, reducing unnecessary re-renders, and streamlining network requests.

Contact our experts immediately if you need more information on how to get started!

Table of contents

FAQs about ReactJs

How does list virtualization benefit React apps?

What is the purpose of using React.Fragment?

How does lazy loading with React.Suspense enhances app performance?

Why should developers use the production build of React?

How does React handle 'this' in functional components?

Pravin Prajapati

Full Stack Developer

Expert in frontend and backend development, combining creativity with sharp technical knowledge. Passionate about keeping up with industry trends, he implements cutting-edge technologies, showcasing strong problem-solving skills and attention to detail in crafting innovative solutions.

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