Benefits of SWR

SWR, which stands for Stale-While-Revalidate, is a strategy derived from HTTP RFC 5861. This approach allows your application to render stale data while asynchronously fetching fresh data in the background, ultimately providing users with updated information.

Advantages of SWR

1. Immediate Rendering and Real-time Updates

   SWR enables your application to display cached (stale) data immediately, followed by background updates with fresh data. This instant display greatly enhances the user experience.

2. Automatic Retries and Polling

   With built-in automatic retries, SWR will persistently attempt to fetch data in case of network failures. Additionally, you can set SWR to periodically poll your server for real-time updates.

Prerequisites for SWR

Before using SWR, ensure that Node.js and npm are installed on your system. You can initialize a new React project using tools like create-react-app, Next.js, or set it up manually.

How to Fetch Data with SWR

To incorporate SWR into your React project, install it using the following commands:

npm install swr

or

yarn add swr

Next, employ the useSWR hook in your component to retrieve data:

import useSWR from 'swr';

function Profile() {

const { data, error, isLoading } = useSWR('/api/user/123', fetcher);

if (error) return <div>Failed to load</div>;

if (isLoading) return <div>Loading...</div>;

return <div>Hello {data.name}!</div>;

}

In this example, useSWR takes two arguments: the URL to fetch and the fetcher function. The hook returns an object with the fetched data and any potential errors.

SWR Configuration Options

SWR offers various configuration options to customize your data fetching behavior. You can provide these settings as the third argument to the useSWR hook or set them globally for all calls.

Common Configuration Options:

• refreshInterval: Defines the polling interval (in milliseconds).
• revalidateOnFocus: Specifies whether SWR should revalidate data when the window regains focus.
• errorRetryCount: Sets the maximum number of retries upon encountering an error.

Error Handling with SWR

SWR has robust error-handling capabilities. If an error occurs during data fetching, the useSWR hook will provide an error object for you to manage.

import useSWR from 'swr';

function Profile() {

const { data, error, isLoading } = useSWR('/api/user/123', fetcher);

if (error) return <div>Failed to load: {error.message}</div>;

if (isLoading) return <div>Loading...</div>;

return <div>Hello {data.name}!</div>;

}

In this snippet, we check for errors using if (error) and display the error message accordingly. While loading, we show a loading indicator, and once data retrieval is complete, we display the fetched information.