---
url: /api/symbols/workbox-window/workbox.md
---

# Workbox

Class workbox-window

A class to aid in handling service worker registration, updates, and
reacting to service worker lifecycle events.

## Constructor

```ts
new Workbox(scriptURL: string | TrustedScriptURL, registerOptions?: object)
```

Creates a new Workbox instance with a script URL and service worker
options. The script URL and options are the same as those used when
calling [navigator.serviceWorker.register(scriptURL, options)](https://developer.mozilla.org/en-US/docs/Web/API/ServiceWorkerContainer/register).

**Parameters**

* `scriptURL` – The service worker script
  associated with this instance. Using a
  [`TrustedScriptURL`](https://web.dev/trusted-types/) is supported.

* `registerOptions` – The service worker options associated
  with this instance.

## Methods

### getSW()

```ts
getSW(): Promise<ServiceWorker>
```

Resolves with a reference to a service worker that matches the script URL
of this instance, as soon as it's available.

If, at registration time, there's already an active or waiting service
worker with a matching script URL, it will be used (with the waiting
service worker taking precedence over the active service worker if both
match, since the waiting service worker would have been registered more
recently).
If there's no matching active or waiting service worker at registration
time then the promise will not resolve until an update is found and starts
installing, at which point the installing service worker is used.

**Returns:**

### messageSkipWaiting()

```ts
messageSkipWaiting(): void
```

Sends a `{type: 'SKIP_WAITING'}` message to the service worker that's
currently in the `waiting` state associated with the current registration.

If there is no current registration or no service worker is `waiting`,
calling this will have no effect.

### messageSW()

```ts
messageSW(data: object): Promise<any>
```

Sends the passed data object to the service worker registered by this
instance (via workbox-window.Workbox#getSW) and resolves
with a response (if any).

A response can be set in a message handler in the service worker by
calling `event.ports[0].postMessage(...)`, which will resolve the promise
returned by `messageSW()`. If no response is set, the promise will never
resolve.

**Parameters**

* `data` – An object to send to the service worker

**Returns:**

### register()

```ts
register(options?: { immediate?: boolean }): Promise<ServiceWorkerRegistration | undefined>
```

Registers a service worker for this instances script URL and service
worker options. By default this method delays registration until after
the window has loaded.

### update()

```ts
update(): Promise<void>
```

Checks for updates of the registered service worker.