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Enhance Long-Reading or Monitoring Sessions via JavaScript Wake Lock

Last updated: December 13, 2024

In the world of web development, providing an optimal user experience is key. One innovative way to enhance the user experience during long reading or monitoring sessions is by leveraging the JavaScript Wake Lock API. This API ensures that users’ devices remain awake, preventing them from dimming or locking automatically, which can interrupt their experience.

The Wake Lock API originated to address problems faced by users who spend lengthy periods reading articles or monitoring dashboards on their devices. A sudden screen lock can break their focus or disrupt data display, causing frustration. The API serves as a reliable solution by keeping the screen active when needed.

Understanding the Wake Lock API

The Wake Lock API is a feature provided by modern web browsers that prevents the device from entering a low-power state. It primarily has two types of locks: screen and system. In this article, we focus on the screen wake lock, which maintains the display as active and prevents it from dimming or sleeping.

Implementing Wake Lock in JavaScript

To set up a Wake Lock, you need to understand the basic implementation steps. The API is asynchronous and uses promises to request a wake lock.

if ('wakeLock' in navigator) {
  let wakeLock = null;

  const requestWakeLock = async () => {
    try {
      wakeLock = await navigator.wakeLock.request('screen');
      console.log('Wake Lock is active');

      wakeLock.addEventListener('release', () => {
        console.log('Wake Lock released');
      });
    } catch (err) {
      console.error(`Wake Lock request failed: ${err.name}, ${err.message}`);
    }
  };

  requestWakeLock();
} else {
  console.log('Wake Lock API not supported');
}

In the above example, we first check if wake lock is supported by the browser. If it is, we attempt to request a screen wake lock. Upon acquiring it, a confirmation message is logged to the console, and an event listener is set to notify us when the lock is released. Proper error handling is included to manage potential failures.

Releasing a Wake Lock

Releasing the wake lock when it's no longer needed is crucial to conserve battery life and system resources. You can manually release the wake lock or set it to release automatically when the page visibility changes or on user interaction.

const releaseWakeLock = async () => {
  if (wakeLock !== null) {
    await wakeLock.release();
    wakeLock = null;
    console.log('Wake Lock released manually');
  }
};

The above code snippet demonstrates how to manually release the wake lock, ensuring the variable is set to null to manage subsequent attempts correctly. Combining these practices ensures a controlled and efficient usage of resources.

Handling Wake Lock Events

The API includes several events and can be managed effectively using event listeners. This approach is effective in scenarios such as lock disruption due to low battery, or a user's manual screen lock.

document.addEventListener('visibilitychange', () => {
  if (document.visibilityState === 'hidden') {
    releaseWakeLock();
  } else {
    requestWakeLock();
  }
});

With this code, we monitor the visibility change of the document. If the tab becomes hidden, it releases the wake lock, conserving energy. Similarly, it re-requests the lock once the document is active again.

Browser Support and Fallbacks

Currently, the Wake Lock API is supported in most modern browsers. However, it is always prudent to provide fallback mechanisms for unsupported environments. For instance, you can notify users to adjust their device settings manually to prevent screen dimming during critical operations.

As the web continues to evolve, the Wake Lock API represents a step toward more interactive and user-centered web experiences. By utilizing this tool wisely, you ensure that long reading or monitoring sessions remain uninterrupted, enhancing user satisfaction and engagement.

Next Article: Maintain Active Displays for Kiosks with the JavaScript Screen Wake Lock API

Previous Article: Improve User Focus by Stopping Screen Dimming in JavaScript

Series: Web APIs – JavaScript Tutorials

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