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.
Properties
This interface inherits properties from the EventTarget
interface and WindowOrWorkerGlobalScope
and WindowEventHandlers
mixins.
Standard properties
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.
Non-standard properties
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.
Properties implemented from elsewhere
WindowOrWorkerGlobalScope.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. WindowOrWorkerGlobalScope.indexedDB
Read only- Provides a mechanism for applications to asynchronously access capabilities of indexed databases; returns an
IDBFactory
object. WindowOrWorkerGlobalScope.isSecureContext
Read only- Returns a boolean indicating whether the current context is secure (
true
) or not (false
). WindowOrWorkerGlobalScope.origin
Read only- Returns the global object's origin, serialized as a string. (This does not yet appear to be implemented in any browser.)
Events
error
- Fired when an error occured. 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 tofalse
. Also available via theWorkerGlobalScope.onoffline
property. online
- Fired when the browser has gained access to the network and the value of
navigator.onLine
switched totrue
. Also available via theWorkerGlobalScope.ononline
property. languagechange
- Fired at the global/worker scope object when the user's preferred languages change. Also available via the
WorkerGlobalScope.onlanguagechange
property.
close
' '- Is an
EventHandler
representing the code to be called when theclose
event is raised. Also available via theWorkerGlobalScope.onclose
property. rejectionhandled
'- An event handler for handled
Promise
rejection events. Also available via theWorkerGlobalScope.onrejectionhandled
property. unhandledrejection
'- An event handler for unhandled
Promise
rejection events. Also available via theWorkerGlobalScope.onunhandledrejection
property.
Methods
This interface inherits methods from the EventTarget
interface and WindowOrWorkerGlobalScope
and WindowEventHandlers
mixins.
Standard methods
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');
Non-standard methods
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.
Methods implemented from elsewhere
WindowOrWorkerGlobalScope.atob()
- Decodes a string of data which has been encoded using base-64 encoding.
WindowOrWorkerGlobalScope.btoa()
- Creates a base-64 encoded ASCII string from a string of binary data.
WindowOrWorkerGlobalScope.clearInterval()
- Cancels the repeated execution set using
WindowOrWorkerGlobalScope.setInterval()
. WindowOrWorkerGlobalScope.clearTimeout()
- Cancels the delayed execution set using
WindowOrWorkerGlobalScope.setTimeout()
. WindowOrWorkerGlobalScope.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. WindowOrWorkerGlobalScope.fetch()
- Starts the process of fetching a resource from the network.
WindowOrWorkerGlobalScope.setInterval()
- Schedules a function to execute every time a given number of milliseconds elapses.
WindowOrWorkerGlobalScope.setTimeout()
- Schedules a function to execute in a given amount of time.
Deprecated methods
WorkerGlobalScope.close()
- Discards any tasks queued in the
WorkerGlobalScope
's event loop, effectively closing this particular scope. In newer browser versions,close()
is available onDedicatedWorkerGlobalScope
andSharedWorkerGlobalScope
instead. This change was made to stopclose()
being available on service workers, as it isn't supposed to be used there and always throws an exception when called (see bug 1336043).
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:
importScripts('foo.js');
console.log(navigator);
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 | Status | Comment |
HTML Living StandardThe definition of 'WorkerGlobalScope' in that specification. | Living Standard |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
WorkerGlobalScope
|
Chrome
Full support 4 |
Edge
Full support 12 |
Firefox
Full support 3.5 |
IE
Full support 10 |
Opera
Full support 10.6 |
Safari
Full support 4 |
WebView Android
Full support Yes |
Chrome Android
Full support Yes |
Firefox Android
Full support 4 |
Opera Android
Full support 11 |
Safari iOS
Full support 3.2 |
Samsung Internet Android
Full support Yes |
Chrome
Full support 4 |
Edge
Full support 12 |
Firefox
Full support 3.5 |
IE
Full support Yes |
Opera
Full support 11.5 |
Safari
Full support 4 |
WebView Android
Full support 37 |
Chrome Android
Full support Yes |
Firefox Android
Full support 4 |
Opera Android
? |
Safari iOS
? |
Samsung Internet Android
Full support Yes | |
Chrome
Full support 4 |
Edge
Full support 12 |
Firefox Full support 29 Full support 29 Notes' Before Firefox 30, the console would be of type |
IE
Full support Yes |
Opera
Full support Yes |
Safari
Full support Yes |
WebView Android
Full support 37 |
Chrome Android
Full support Yes |
Firefox Android Full support 29 Full support 29 Notes' Before Firefox 30, the console would be of type |
Opera Android
? |
Safari iOS
? |
Samsung Internet Android
Full support Yes | |
Chrome
No support No |
Edge
No support No |
Firefox
No support No |
IE
No support No |
Opera
No support No |
Safari
No support No |
WebView Android
No support No |
Chrome Android
No support No |
Firefox Android
Full support 4 |
Opera Android
No support No |
Safari iOS
No support No |
Samsung Internet Android
No support No | |
importScripts
|
Chrome
Full support 4 |
Edge
Full support 12 |
Firefox
Full support 4 |
IE
Full support 10 |
Opera
Full support 10.6 |
Safari
Full support 4 |
WebView Android
Full support ≤37 |
Chrome Android
Full support 18 |
Firefox Android
Full support 4 |
Opera Android
Full support 11 |
Safari iOS
Full support 3.2 |
Samsung Internet Android
Full support 1.0 |
languagechange event
|
Chrome
Full support 4 |
Edge
Full support 12 |
Firefox
Full support 74 |
IE
Full support Yes |
Opera
Full support 11.5 |
Safari
Full support 4 |
WebView Android
? |
Chrome Android
Full support 40 |
Firefox Android
No support No |
Opera Android
Full support Yes |
Safari iOS
Full support 5.1 |
Samsung Internet Android
Full support 4.0 |
location
|
Chrome
Full support 4 |
Edge
Full support 12 |
Firefox
Full support 3.5 |
IE
Full support Yes |
Opera
Full support 11.5 |
Safari
Full support 4 |
WebView Android
Full support 37 |
Chrome Android
Full support 40 |
Firefox Android
Full support 4 |
Opera Android
Full support Yes |
Safari iOS
Full support 5.1 |
Samsung Internet Android
Full support 4.0 |
navigator
|
Chrome
Full support 4 |
Edge
Full support 17 |
Firefox
Full support 3.5 |
IE
Full support Yes |
Opera
Full support 11.5 |
Safari
Full support 4 |
WebView Android
Full support 37 |
Chrome Android
Full support 40 |
Firefox Android
Full support 4 |
Opera Android
Full support Yes |
Safari iOS
Full support 5.1 |
Samsung Internet Android
Full support 4.0 |
Chrome
Full support 4 |
Edge
Full support 12 |
Firefox
No support 3.5 — 50 |
IE
Full support Yes |
Opera
Full support 11.5 |
Safari
Full support 4 |
WebView Android
Full support 37 |
Chrome Android
Full support 40 |
Firefox Android
No support 4 — 50 |
Opera Android
Full support Yes |
Safari iOS
Full support 5.1 |
Samsung Internet Android
Full support 4.0 | |
onerror
|
Chrome
Full support 4 |
Edge
Full support 12 |
Firefox
Full support 3.5 |
IE
Full support Yes |
Opera
Full support 11.5 |
Safari
Full support 4 |
WebView Android
Full support 37 |
Chrome Android
Full support 40 |
Firefox Android
Full support 4 |
Opera Android
Full support Yes |
Safari iOS
Full support 5.1 |
Samsung Internet Android
Full support 4.0 |
onlanguagechange
|
Chrome
Full support 4 |
Edge
Full support 12 |
Firefox
Full support 74 |
IE
Full support Yes |
Opera
Full support 11.5 |
Safari
Full support 4 |
WebView Android
Full support 37 |
Chrome Android
Full support 40 |
Firefox Android
No support No |
Opera Android
Full support Yes |
Safari iOS
Full support 5.1 |
Samsung Internet Android
Full support 4.0 |
onoffline
|
Chrome
Full support 4 |
Edge
Full support ≤79 |
Firefox
Full support 29 |
IE
No support No |
Opera
? |
Safari
? |
WebView Android
Full support Yes |
Chrome Android
Full support 40 |
Firefox Android
Full support 29 |
Opera Android
? |
Safari iOS
? |
Samsung Internet Android
Full support 4.0 |
ononline
|
Chrome
Full support 4 |
Edge
Full support ≤79 |
Firefox
Full support 29 |
IE
No support No |
Opera
? |
Safari
? |
WebView Android
Full support Yes |
Chrome Android
Full support 40 |
Firefox Android
Full support 29 |
Opera Android
? |
Safari iOS
? |
Samsung Internet Android
Full support 4.0 |
performance
|
Chrome
Full support Yes |
Edge
Full support ≤79 |
Firefox
Full support 34 |
IE
No support No |
Opera
? |
Safari
? |
WebView Android
Full support Yes |
Chrome Android
Full support Yes |
Firefox Android
Full support 34 |
Opera Android
? |
Safari iOS
? |
Samsung Internet Android
Full support Yes |
self
|
Chrome
Full support 4 |
Edge
Full support 12 |
Firefox
Full support 3.5 |
IE
Full support Yes |
Opera
Full support 11.5 |
Safari
Full support 4 |
WebView Android
Full support 37 |
Chrome Android
Full support 40 |
Firefox Android
Full support 34 |
Opera Android
Full support Yes |
Safari iOS
Full support 5.1 |
Samsung Internet Android
Full support 4.0 |
Legend
- Full support
- Full support
- No support
- No support
- Compatibility unknown
- Compatibility unknown
- Non-standard. Expect poor cross-browser support.'
- Non-standard. Expect poor cross-browser support.
- Deprecated. Not for use in new websites.'
- Deprecated. Not for use in new websites.
- See implementation notes.'
- See implementation notes.
See also
- Other global object interface:
Window
,DedicatedWorkerGlobalScope
,SharedWorkerGlobalScope
, ,ServiceWorkerGlobalScope
- Other Worker-related interfaces:
Worker
,WorkerLocation
,WorkerGlobalScope
, andServiceWorkerGlobalScope
. - Using web workers.
WorkerGlobalScope by Mozilla Contributors is licensed under CC-BY-SA 2.5.