In this section, you will be learning about a performance technique called lazy loading; the basics and why it is important for improving application performance in React apps. By the end of this section, you will have good understanding of what and how to use this technique in your React projects.

What is Code Splitting?

Code splitting in React is a technique used to split your application’s code into smaller chunks, so that only the necessary code is loaded initially, and the rest is loaded dynamically as needed. This improves the performance of your app by reducing the initial load time, as the browser doesn't have to download the entire JavaScript bundle at once.

How Code Splitting Works in React

In React, code splitting is typically done using dynamic import() statements and tools like React.lazy and Suspense. When a component is wrapped in React.lazy(), it tells the browser to load that component asynchronously when it's required, rather than including it in the initial JavaScript bundle.

Why use code splitting?

There are benefits of using this technique, such as;

• Faster initial load: By only loading what’s necessary for the initial page render, your app can start faster.

• Better user experience: Since additional code is loaded only when needed, it ensures that the app stays responsive and doesn’t freeze during the initial load.

• More efficient resource usage: Code splitting helps reduce memory and bandwidth usage by only downloading the code required for a specific page or feature.

Code splitting can be done more extensively with bundlers like Webpack, but React's built-in features make it easy to implement at the component level.

What is Lazy Loading?

Lazy loading is a performance optimization technique that delays the loading of resources (like JavaScript, images, or components) until they are needed by the application. In the context of React, lazy loading allows components, images, and routes to be loaded only when required, which significantly improves the initial page load time.

React provides built-in tools like React.lazy() and React.Suspense to facilitate lazy loading, particularly for dynamic imports.

How Lazy Loading Works in React

In React, lazy loading is often used to load components on demand, instead of loading all components upfront. This is particularly useful for large applications with many routes or components that are not required immediately.

Why Use Lazy Loading?

There are numerous benefits of using this technique, such as;

• Improves Initial Load Time – Only the necessary components are loaded initially.
• Reduces JavaScript Bundle Size – Large applications can break down into smaller chunks.
• Optimizes Performance – Users experience a faster page load time.
• Efficient Resource Utilization – Saves bandwidth by loading only needed content.

How Do Code Splitting and Lazy Loading Relate?

These terms are sometimes used interchangeably, but to clarify their relationship, here are the key points to understand:

• Lazy loading is a specific form of code splitting.
• Code splitting is the broader technique of splitting the code into smaller bundles, while lazy loading refers to loading those smaller chunks only when required.

So, in summary: Lazy loading is one way to implement code splitting, specifically for components that don’t need to be loaded immediately, improving the app's performance.

In the next lessons, we will be taking a deeper look at these techniques and how you can leverage them to improve your React app's efficiency.