WorkerGlobalScope
The WorkerGlobalScope
interface of the Web Workers API is an interface representing the scope of any worker. Workers have no browsing context; this scope contains the information usually conveyed by Window
objects — in this case event handlers, the console or the associated WorkerNavigator
object. Each WorkerGlobalScope
has its own event loop.
This interface is usually specialized by each worker type: DedicatedWorkerGlobalScope
for dedicated workers, SharedWorkerGlobalScope
for shared workers, and ServiceWorkerGlobalScope
for ServiceWorker. The self
property returns the specialized scope for each context.
Instance properties
This interface inherits properties from the EventTarget
interface.
Standard properties
WorkerGlobalScope.caches
Read only-
Returns the
CacheStorage
object associated with the current context. This object enables functionality such as storing assets for offline use, and generating custom responses to requests. WorkerGlobalScope.fonts
Read only-
Returns the
FontFaceSet
associated with the worker. WorkerGlobalScope.indexedDB
Read only-
Provides a mechanism for applications to asynchronously access capabilities of indexed databases; returns an
IDBFactory
object. WorkerGlobalScope.isSecureContext
Read only-
Returns a boolean indicating whether the current context is secure (
true
) or not (false
). WorkerGlobalScope.location
Read only-
Returns the
WorkerLocation
associated with the worker. It is a specific location object, mostly a subset of theLocation
for browsing scopes, but adapted to workers.r. -
Returns the
WorkerNavigator
associated with the worker. It is a specific navigator object, mostly a subset of theNavigator
for browsing scopes, but adapted to workers. WorkerGlobalScope.origin
Read only-
Returns the global object's origin, serialized as a string.
WorkerGlobalScope.performance
Read only-
Returns the
Performance
associated with the worker. It is a regular performance object, except that only a subset of its property and methods are available to workers. WorkerGlobalScope.scheduler
Read only-
Returns the
Scheduler
object associated with the current context. This is the entry point for using the Prioritized Task Scheduling API. WorkerGlobalScope.self
Read only-
Returns a reference to the
WorkerGlobalScope
itself. Most of the time it is a specific scope likeDedicatedWorkerGlobalScope
,SharedWorkerGlobalScope
orServiceWorkerGlobalScope
.
Non-standard properties
WorkerGlobalScope.console
Read only Non-standard-
Returns the
console
associated with the worker.
Instance methods
This interface inherits methods from the EventTarget
interface.
Standard methods
WorkerGlobalScope.atob()
-
Decodes a string of data which has been encoded using base-64 encoding.
WorkerGlobalScope.btoa()
-
Creates a base-64 encoded ASCII string from a string of binary data.
WorkerGlobalScope.clearInterval()
-
Cancels the repeated execution set using
setInterval()
. WorkerGlobalScope.clearTimeout()
-
Cancels the delayed execution set using
setTimeout()
. WorkerGlobalScope.createImageBitmap()
-
Accepts a variety of different image sources, and returns a
Promise
which resolves to anImageBitmap
. Optionally the source is cropped to the rectangle of pixels originating at (sx, sy) with width sw, and height sh. WorkerGlobalScope.fetch()
-
Starts the process of fetching a resource from the network.
WorkerGlobalScope.importScripts()
-
Imports one or more scripts into the worker's scope. You can specify as many as you'd like, separated by commas. For example:
importScripts('foo.js', 'bar.js');
WorkerGlobalScope.setInterval()
-
Schedules a function to execute every time a given number of milliseconds elapses.
WorkerGlobalScope.setTimeout()
-
Schedules a function to execute in a given amount of time.
WorkerGlobalScope.reportError()
-
Reports an error in a script, emulating an unhandled exception.
Non-standard methods
WorkerGlobalScope.dump()
Deprecated Non-standard-
Allows you to write a message to stdout — i.e. in your terminal. This is the same as Firefox's
window.dump
, but for workers.
Events
error
-
Fires when an error occurred.
offline
-
Fires when the browser has lost access to the network and the value of
navigator.onLine
switched tofalse
. online
-
Fires when the browser has gained access to the network and the value of
navigator.onLine
switched totrue
. languagechange
-
Fires at the global/worker scope object when the user's preferred languages change.
rejectionhandled
Non-standard-
Fires on handled
Promise
rejection events. unhandledrejection
Non-standard-
Fires on unhandled
Promise
rejection events.
Example
You won't access WorkerGlobalScope
directly in your code; however, its properties and methods are inherited by more specific global scopes such as DedicatedWorkerGlobalScope
and SharedWorkerGlobalScope
. For example, you could import another script into the worker and print out the contents of the worker scope's navigator
object using the following two lines:
js
importScripts("foo.js");
console.log(navigator);
Note: Since the global scope of the worker script is effectively the global scope of the worker you are running (DedicatedWorkerGlobalScope
or whatever) and all worker global scopes inherit methods, properties, etc. from WorkerGlobalScope
, you can run lines such as those above without specifying a parent object.
Specifications
Specification |
---|
HTML Standard # the-workerglobalscope-common-interface |
Browser compatibility
BCD tables only load in the browser
See also
- Other global object interface:
Window
,DedicatedWorkerGlobalScope
,SharedWorkerGlobalScope
,ServiceWorkerGlobalScope
- Other Worker-related interfaces:
Worker
,WorkerLocation
,WorkerGlobalScope
, andServiceWorkerGlobalScope
- Using web workers