Service Workers

Class: ServiceWorkers

Query and receive events from a sessions active service workers.

Process: Main

This class is not exported from the 'electron' module. It is only available as a return value of other methods in the Electron API.

Instances of the ServiceWorkers class are accessed by using serviceWorkers property of a Session.

For example:

const { session } = require('electron')

// Get all service workers.
console.log(session.defaultSession.serviceWorkers.getAllRunning())

// Handle logs and get service worker info
session.defaultSession.serviceWorkers.on('console-message', (event, messageDetails) => {
  console.log(
    'Got service worker message',
    messageDetails,
    'from',
    session.defaultSession.serviceWorkers.getFromVersionID(messageDetails.versionId)
  )
})

Instance Events

The following events are available on instances of ServiceWorkers:

Event: 'console-message'

Returns:

• event Event
• messageDetails Object - Information about the console message
  • message string - The actual console message
  • versionId number - The version ID of the service worker that sent the log message
  • source string - The type of source for this message. Can be javascript, xml, network, console-api, storage, rendering, security, deprecation, worker, violation, intervention, recommendation or other.
  • level number - The log level, from 0 to 3. In order it matches verbose, info, warning and error.
  • sourceUrl string - The URL the message came from
  • lineNumber number - The line number of the source that triggered this console message

Emitted when a service worker logs something to the console.

Event: 'registration-completed'

Returns:

• event Event
• details Object - Information about the registered service worker
  • scope string - The base URL that a service worker is registered for

Emitted when a service worker has been registered. Can occur after a call to navigator.serviceWorker.register('/sw.js') successfully resolves or when a Chrome extension is loaded.

Event: 'running-status-changed' Experimental

Returns:

• details Event<>
  • versionId number - ID of the updated service worker version
  • runningStatus string - Running status. Possible values include starting, running, stopping, or stopped.

Emitted when a service worker's running status has changed.

Instance Methods

The following methods are available on instances of ServiceWorkers:

serviceWorkers.getAllRunning()

Returns Record<number, ServiceWorkerInfo> - A ServiceWorkerInfo object where the keys are the service worker version ID and the values are the information about that service worker.

serviceWorkers.getInfoFromVersionID(versionId)

• versionId number - ID of the service worker version

Returns ServiceWorkerInfo - Information about this service worker

If the service worker does not exist or is not running this method will throw an exception.

serviceWorkers.getFromVersionID(versionId) Deprecated

• versionId number - ID of the service worker version

Returns ServiceWorkerInfo - Information about this service worker

If the service worker does not exist or is not running this method will throw an exception.

Deprecated: Use the new serviceWorkers.getInfoFromVersionID API.

serviceWorkers.getWorkerFromVersionID(versionId) Experimental

• versionId number - ID of the service worker version

Returns ServiceWorkerMain | undefined - Instance of the service worker associated with the given version ID. If there's no associated version, or its running status has changed to 'stopped', this will return undefined.

serviceWorkers.startWorkerForScope(scope) Experimental

• scope string - The scope of the service worker to start.

Returns Promise<ServiceWorkerMain> - Resolves with the service worker when it's started.

Starts the service worker or does nothing if already running.

const { app, session } = require('electron')

const { serviceWorkers } = session.defaultSession

// Collect service workers scopes
const workerScopes = Object.values(serviceWorkers.getAllRunning()).map((info) => info.scope)

app.on('browser-window-created', async (event, window) => {
  for (const scope of workerScopes) {
    try {
      // Ensure worker is started
      const serviceWorker = await serviceWorkers.startWorkerForScope(scope)
      serviceWorker.send('window-created', { windowId: window.id })
    } catch (error) {
      console.error(`Failed to start service worker for ${scope}`)
      console.error(error)
    }
  }
})