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Lazy Loading with React–An Overview

Lazy loading is likely one of the most typical design patterns utilized in net and cell growth. It’s extensively used with frameworks like Angular and React to extend an software’s efficiency by lowering preliminary loading time.

Within the earlier variations of React, lazy loading was applied utilizing third-party libraries. Nevertheless, React launched two new native options to implement lazy loading with the React v16.6 replace.

On this article, I’ll focus on what lazy loading is, tips on how to implement it with React, and its professionals and cons.

What Is Lazy Loading?

In easy phrases, lazy loading is a design sample. It lets you load components of your software on-demand to cut back the preliminary load time. For instance, you possibly can initially load the parts and modules associated to consumer login and registration. Then, you possibly can load the remainder of the parts based mostly on consumer navigation.

You may not really feel a lot distinction when utilizing lazy loading for small-scale purposes. Nevertheless it considerably impacts large-scale purposes by lowering the preliminary load time. In the end, it improves each the consumer expertise and the applying’s efficiency.

Benefits of Lazy Loading

  • Reduces preliminary loading time by lowering the bundle dimension.
  • Reduces browser workload.
  • Improves software efficiency in low bandwidth conditions.
  • Improves consumer expertise at preliminary loading.
  • Optimizes useful resource utilization.

Disadvantages of Lazy Loading

  • Not appropriate for small-scale purposes.
  • Placeholders can decelerate fast scrolling.
  • Requires extra communication with the server to fetch sources.
  • Can have an effect on website positioning and rating.

Implementing Lazy Loading with React

Normally, lazy loading isn’t utilized in React purposes, since we largely use React to develop single-page purposes. Builders can bundle your entire code as a single bundle and use it for deployments.

However, as the applying will get complicated, we have to take into account efficiency and consumer expertise. In such conditions, we have to use the lazy-loading strategies out there with React to bundle the crucial and noncritical components of the applying individually.

You should use fashionable bundlers and transpilers like Webpack and Babel to implement purposes following the modular sample. Then, you should use code splitting to divide the applying bundle into smaller ones and lazy load them.

React launched two native options with the model 16.6 launch to implement lazy loading in React purposes. First, they use the ability of code splitting and dynamic imports to permit builders to implement lazy loading for his or her purposes simply.

So, let’s see how we are able to implement lazy loading in React.


React.lazy() permits builders to simply create parts with dynamic imports and render them as regular parts. When the element is rendered, it is going to mechanically load the bundle that incorporates the rendered element.

It is advisable present a single enter parameter to name React.lazy(). It accepts a perform as an enter parameter, and that perform ought to return a promise after loading the element utilizing import(). Lastly, the returned promise from React.lazy() provides you with a module with a default export containing the React element.

The next code reveals tips on how to use the React.lazy() perform.

// With out React.lazy()
import AboutComponent from './AboutComponent ';

// With React.lazy()
const AboutComponent = React.lazy(() => import('./AboutComponent '));

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


After we use lazy loading, parts are rendered as we navigate. So, we have to have a placeholder for these parts till they’re loaded. As an answer, React.Suspense was launched, and it acts as a wrapper for the lazy parts.

You’ll be able to wrap a single lazy element, a number of lazy parts, or a number of lazy parts with completely different hierarchy ranges with React.Suspense. As well as, it accepts a prop named fallback because the placeholder, and you’ll cross a element or a component for that.

For instance, you possibly can cross the ready or loading message because the fallback prop, and it is going to be displayed till the wrapped lazy element is rendered.

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

const HomeComponent = () => (
    <div><Suspense fallback = { <div> Please Wait... </div> } >
            <AboutComponent /></Suspense></div>

As you possibly can see, it’s essential use each the React.lazy() and React.Suspense options to construct a lazy-loading element in React. These options are easy and anybody with fundamental React information can simply use them.

Nevertheless, typically you would possibly face points as a result of promise rejections within the React.lazy() perform. To beat such conditions, it’s essential create a React error boundary element and wrap the Suspense parts utilizing it.

import React, { Suspense } from "react";
import ErrorBoundary from "./error.boundary.js";
const AboutComponent = React.lazy(() => import('./AboutComponent'));

const HomeComponent = () => (
        <Suspense fallback = { <div> Please Wait... </div>} >
          <AboutComponent /></Suspense></ErrorBoundary>

Don’t Use Too A lot Lazy Loading

As mentioned, lazy loading has many advantages. However overusing it might have a big damaging affect in your purposes. So, it’s important to grasp after we ought to use lazy loading and after we shouldn’t.

You shouldn’t go for lazy loading in case your software has a small bundle dimension. There is no such thing as a level in splitting a small bundle into items, and it’ll solely improve coding and configuring effort.

Additionally, there are particular software sorts like e-commerce websites that may be damaging impacted by lazy loading. For instance, customers wish to scroll by means of shortly when trying to find gadgets. In case you lazy load buying gadgets, it is going to break the scrolling pace and lead to a foul consumer expertise. So, it is best to analyze the corporate’s web site utilization earlier than utilizing lazy loading.

Then again, lazy loading generally is a actual life-saver in large-scale tasks. Initiatives with massive bundle sizes take a big period of time for the preliminary load, and it’s a vital disadvantage by way of consumer expertise. So, consider software necessities, scale, and present efficiency of the applying earlier than selecting lazy loading.


This text mentioned what lazy loading is, how we are able to implement it in React, and the professionals and cons we must always know earlier than utilizing it. I hope this text helped you enhance your information of React lazy loading.

Thanks for studying.

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