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Sessions Decorators

The Sessions decorators allow you to easily respond to browser session events in your extension services.

Method Decorators​

onSessionChanged​

This decorator handles events that fire when recently closed tabs and/or windows are changed. This can happen when tabs or windows are closed or restored from the browser's session history.

import { onSessionChanged, InjectableService } from 'deco-ext';

@InjectableService()
class SessionService {
  @onSessionChanged()
  handleSessionChange() {
    // This event doesn't provide any arguments
    console.log('Session changed - recently closed tabs/windows were modified');
    
    // You might want to fetch the current session data:
    this.getRecentlyClosedItems();
  }
  
  private async getRecentlyClosedItems() {
    const sessions = await browser.sessions.getRecentlyClosed();
    console.log('Recent sessions:', sessions);
  }
}

Parameter Decorators​

No parameter decorators are available for the onSessionChanged decorator since the browser event doesn't provide any arguments.

Implementation Details​

This decorator uses a singleton pattern to ensure only one event listener is registered, and then routes events to all decorated methods. When a session change event occurs:

  1. The event is received by the single registered browser API listener
  2. Each registered method handler is called
  3. For each handler:
    • The class instance is resolved from the dependency injection container
    • If the class has an init method, it's called before handling the event
    • The method is called with no parameters

The decorator can only be used on methods within classes that have been decorated with the InjectableService decorator from deco-ext.

Working with Sessions​

While the onSessionChanged event itself doesn't provide arguments, you can use the browser.sessions API to:

  • Retrieve recently closed tabs and windows with browser.sessions.getRecentlyClosed()
  • Restore closed tabs with browser.sessions.restore(sessionId)
  • Get device information with browser.sessions.getDevices()

Example of restoring the most recently closed tab:

import { onSessionChanged, InjectableService } from 'deco-ext';

@InjectableService()
class SessionService {
  @onSessionChanged()
  async handleSessionChange() {
    // Get recently closed sessions
    const sessions = await browser.sessions.getRecentlyClosed();
    
    // Find the most recently closed tab
    const recentTab = sessions.find(session => session.tab);
    
    if (recentTab && recentTab.tab) {
      console.log(`Most recently closed tab: ${recentTab.tab.title}`);
      
      // You could potentially auto-restore it
      // await browser.sessions.restore(recentTab.tab.sessionId);
    }
  }
}