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.
This interface inherits properties from the EventTarget
interface and WindowOrWorkerGlobalScope
and WindowEventHandlers
mixins.
WorkerGlobalScope.navigator
Read only
Returns the WorkerNavigator
associated with the worker. It is a specific navigator object, mostly a subset of the Navigator
for browsing scopes, but adapted to workers.
WorkerGlobalScope.self
Read only
Returns a reference to the WorkerGlobalScope
itself. Most of the time it is a specific scope like DedicatedWorkerGlobalScope
, SharedWorkerGlobalScope
or ServiceWorkerGlobalScope
.
WorkerGlobalScope.location
Read only
Returns the WorkerLocation
associated with the worker. It is a specific location object, mostly a subset of the Location
for browsing scopes, but adapted to workers.
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.console
Read only
Returns the console
associated with the worker.
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.
indexedDB
Read only
Provides a mechanism for applications to asynchronously access capabilities of indexed databases; returns an IDBFactory
object.
isSecureContext
Read only
Returns a boolean indicating whether the current context is secure (true
) or not (false
).
origin
Read only
Returns the global object's origin, serialized as a string. (This does not yet appear to be implemented in any browser.)
error
Fired when an error occurred. Also available via the WorkerGlobalScope.onerror
property.
offline
Fired when the browser has lost access to the network and the value of navigator.onLine
switched to false
. Also available via the WorkerGlobalScope.onoffline
property.
online
Fired when the browser has gained access to the network and the value of navigator.onLine
switched to true
. Also available via the WorkerGlobalScope.ononline
property.
languagechange
Fired at the global/worker scope object when the user's preferred languages change. Also available via the WorkerGlobalScope.onlanguagechange
property.
rejectionhandled
An event handler for handled Promise
rejection events. Also available via the WorkerGlobalScope.onrejectionhandled
property.
unhandledrejection
An event handler for unhandled Promise
rejection events. Also available via the WorkerGlobalScope.onunhandledrejection
property.
This interface inherits methods from the EventTarget
interface and WindowOrWorkerGlobalScope
and WindowEventHandlers
mixins.
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.dump()
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.
atob()
Decodes a string of data which has been encoded using base-64 encoding.
btoa()
Creates a base-64 encoded ASCII string from a string of binary data.
clearInterval()
Cancels the repeated execution set using setInterval()
.
clearTimeout()
Cancels the delayed execution set using setTimeout()
.
createImageBitmap()
Accepts a variety of different image sources, and returns a Promise
which resolves to an ImageBitmap
. Optionally the source is cropped to the rectangle of pixels originating at (sx, sy) with width sw, and height sh.
fetch()
Starts the process of fetching a resource from the network.
setInterval()
Schedules a function to execute every time a given number of milliseconds elapses.
setTimeout()
Schedules a function to execute in a given amount of time.
reportError()
Reports an error in a script, emulating an unhandled exception.
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:
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.
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
WorkerGlobalScope |
4 |
12 |
3.5 |
10 |
10.6 |
4 |
≤37 |
18 |
4 |
11 |
5 |
1.0 |
dump |
No |
No |
No |
No |
No |
No |
No |
No |
4 |
No |
No |
No |
importScripts |
4 |
12 |
4 |
10 |
10.6 |
4 |
≤37 |
18 |
4 |
11 |
5 |
1.0 |
languagechange_event |
4 |
79 |
74 |
No |
11.5 |
4 |
≤37 |
40 |
No |
Yes |
5 |
4.0 |
location |
4 |
12 |
3.5 |
10 |
11.5 |
4 |
37 |
40 |
4 |
Yes |
5 |
4.0 |
navigator |
4 |
17 |
3.5 |
10 |
11.5 |
4 |
37 |
40 |
4 |
Yes |
5 |
4.0 |
onerror |
4 |
12 |
3.5 |
10 |
11.5 |
4 |
37 |
40 |
4 |
Yes |
5 |
4.0 |
onlanguagechange |
4 |
79 |
74 |
No |
11.5 |
4 |
37 |
40 |
No |
Yes |
5 |
4.0 |
onoffline |
4 |
≤79 |
29 |
No |
? |
8 |
40 |
40 |
29 |
? |
8 |
4.0 |
ononline |
4 |
≤79 |
29 |
No |
? |
8 |
40 |
40 |
29 |
? |
8 |
4.0 |
self |
4 |
12 |
3.5 |
10 |
11.5 |
4 |
37 |
40 |
34 |
Yes |
5 |
4.0 |
Window
, DedicatedWorkerGlobalScope
, SharedWorkerGlobalScope
, , ServiceWorkerGlobalScope
Worker
, WorkerLocation
, WorkerGlobalScope
, and ServiceWorkerGlobalScope
.
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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/WorkerGlobalScope