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Using Beacon for Send-At-Last-Moment Data Like Form Drafts

Last updated: December 12, 2024

In the realm of modern web development, handling user interacts effectively is paramount to delivering optimal user experiences. One powerful tool at your disposal in achieving this functionality is the Fetch API, and more specifically, its Beacon API extension. The Beacon API allows developers to send data to a web server in the background with minimal impact on the main thread, making it ideal for tasks like sending form drafts right as a user navigates away from the page or closes the tab.

The key advantage of the Beacon API is its non-blocking characteristic, ensuring seamless user interactions while data is sent in the background. This allows developers to capture form drafts or track user activities efficiently without sacrificing performance. In this article, we will explore how the Beacon API works and why it's particularly suited for send-at-last-moment scenarios like saving form drafts.

Understanding the Beacon API

Introduced with the other Fetch API capabilities, the Beacon API comes in handy when small amounts of data need to be sent back to the server without blocking user navigation. It is especially designed for analytics and diagnostics, functioning smoothly even when a document is being unloaded. Here's how you can leverage the Beacon API within your own web applications.

Basic Usage

The basic premise of the Beacon API revolves around the navigator.sendBeacon() method. This method sends data asynchronously to a server. Below is a simple example of how it can be used.

const formDraftData = new Blob([JSON.stringify({title: "Post Title", content: "Post Content"})], {type : 'application/json'});

// URL to send the data to
const draftEndpoint = 'https://example.com/storeDraft';

navigator.sendBeacon(draftEndpoint, formDraftData);

In this example, a JSON object representing draft data is created and sent to a specified endpoint using the sendBeacon method. This uses a Blob to handle data which is ideal for binary tasks and fits well within this API’s design.

Use Case: Saving Form Drafts

One common scenario where the Beacon API shines is in saving form drafts. Suppose you're developing a blog platform, and your users often write lengthy articles. Users may accidentally navigate away from the page or close the browser/tab. In such instances, it's crucial to save their progress at the last moment. Here's how you could implement an autosave feature for form drafts using the Beacon API:

window.addEventListener('beforeunload', (event) => {
  const formDraftData = new Blob([JSON.stringify({
    title: document.querySelector('#title').value,
    content: document.querySelector('#content').value
  })], {type : 'application/json'});

  // Endpoint for saving drafts
  const draftSaveUrl = 'https://example.com/api/drafts';

  // Use navigator.sendBeacon to asynchronously send the form data
  navigator.sendBeacon(draftSaveUrl, formDraftData);
});

In this code snippet, an event listener is set up on the window's beforeunload event. This allows you to intercept events when a user may leave the page, and utilizing sendBeacon ensures that the draft data is sent out asynchronously as the document begins unloading. The saved data is usually caught by a backend service that stores the drafts until users wish to return to their session.

Benefits and Considerations

While the Beacon API proves advantageous, there are some considerations to understand:

  • Minimal Interference: Unlike XMLHttpRequest or Fetch, which are subject to potential failing due to unloading behavior, Beacon requests play well with page unloading, enhancing user experiences by reducing unnecessary callbacks.
  • Data Limitations: Beacons are intended for small amounts of data (about 64Kb or less). For larger tasks, chunking data over multiple requests may be necessary.
  • No Response Handling: It’s important to note that sendBeacon does not provide response data. It's purely a one-way mechanism to inform and update updates without requiring any feedback.

By integrating the Beacon API into your web application, especially for scenarios like form drafts, you're ensuring that important user data is captured and stored appropriately, enhancing the value and reliability of your platform.

Next Article: Background Sync for Reliable Offline-to-Online Data Synchronization

Previous Article: Combining the Badging API with Notifications for Better User Engagement

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