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WorkerGlobalScope

files/en-us/web/api/workerglobalscope/index.md

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{{APIRef("Web Workers API")}}{{AvailableInWorkers("worker")}}

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 {{domxref("Window")}} objects — in this case event handlers, the console or the associated {{domxref("WorkerNavigator")}} object. Each WorkerGlobalScope has its own event loop.

This interface is usually specialized by each worker type: {{domxref("DedicatedWorkerGlobalScope")}} for dedicated workers, {{domxref("SharedWorkerGlobalScope")}} for shared workers, and {{domxref("ServiceWorkerGlobalScope")}} for ServiceWorker. The self property returns the specialized scope for each context.

{{InheritanceDiagram}}

Instance properties

This interface inherits properties from the {{domxref("EventTarget")}} interface.

  • {{domxref("WorkerGlobalScope.caches")}} {{ReadOnlyInline}} {{SecureContext_Inline}}
    • : Returns the {{domxref("CacheStorage")}} object associated with the current context. This object enables functionality such as storing assets for offline use, and generating custom responses to requests.
  • {{domxref("WorkerGlobalScope.crossOriginIsolated")}} {{ReadOnlyInline}}
    • : Returns a boolean value that indicates whether the website is in a cross-origin isolation state.
  • {{domxref("WorkerGlobalScope.crypto")}} {{ReadOnlyInline}}
    • : Returns the {{domxref("Crypto")}} object associated to the global object.
  • {{domxref("WorkerGlobalScope.fonts")}} {{ReadOnlyInline}}
    • : Returns the {{domxref("FontFaceSet")}} associated with the worker.
  • {{domxref("WorkerGlobalScope.indexedDB")}} {{ReadOnlyInline}}
    • : Provides a mechanism for workers to asynchronously access capabilities of indexed databases; returns an {{domxref("IDBFactory")}} object.
  • {{domxref("WorkerGlobalScope.isSecureContext")}} {{ReadOnlyInline}}
    • : Returns a boolean indicating whether the current context is secure (true) or not (false).
  • {{domxref("WorkerGlobalScope.location")}} {{ReadOnlyInline}}
    • : Returns the {{domxref("WorkerLocation")}} associated with the worker. It is a specific location object, mostly a subset of the {{domxref("Location")}} for browsing scopes, but adapted to workers.
  • {{domxref("WorkerGlobalScope.navigator")}} {{ReadOnlyInline}}
    • : Returns the {{domxref("WorkerNavigator")}} associated with the worker. It is a specific navigator object, mostly a subset of the {{domxref("Navigator")}} for browsing scopes, but adapted to workers.
  • {{domxref("WorkerGlobalScope.origin")}} {{ReadOnlyInline}}
    • : Returns the global object's origin, serialized as a string.
  • {{domxref("WorkerGlobalScope.performance")}} {{ReadOnlyInline}}
    • : Returns the {{domxref("Performance")}} associated with the worker. Only a subset of the properties and methods of the Performance interface are available to workers.
  • {{domxref("WorkerGlobalScope.scheduler")}} {{ReadOnlyInline}}
    • : Returns the {{domxref("Scheduler")}} object associated with the current context. This is the entry point for using the Prioritized Task Scheduling API.
  • {{domxref("WorkerGlobalScope.trustedTypes")}} {{ReadOnlyInline}}
    • : Returns the {{domxref("TrustedTypePolicyFactory")}} object associated with the global object, providing the entry point for using the {{domxref("Trusted Types API", "", "", "nocode")}}.
  • {{domxref("WorkerGlobalScope.self")}} {{ReadOnlyInline}}
    • : Returns a reference to the WorkerGlobalScope itself. Most of the time it is a specific scope like {{domxref("DedicatedWorkerGlobalScope")}}, {{domxref("SharedWorkerGlobalScope")}} or {{domxref("ServiceWorkerGlobalScope")}}.

Instance methods

This interface inherits methods from the {{domxref("EventTarget")}} interface.

  • {{domxref("WorkerGlobalScope.atob()")}}
    • : Decodes a string of data which has been encoded using base-64 encoding.
  • {{domxref("WorkerGlobalScope.btoa()")}}
    • : Creates a base-64 encoded {{Glossary("ASCII")}} string from a string of binary data.
  • {{domxref("WorkerGlobalScope.clearInterval()")}}
    • : Cancels the repeated execution set using {{domxref("WorkerGlobalScope.setInterval()")}}.
  • {{domxref("WorkerGlobalScope.clearTimeout()")}}
    • : Cancels the delayed execution set using {{domxref("WorkerGlobalScope.setTimeout()")}}.
  • {{domxref("WorkerGlobalScope.createImageBitmap()")}}
    • : Accepts a variety of different image sources, and returns a {{jsxref("Promise")}} which resolves to an {{domxref("ImageBitmap")}}. Optionally the source is cropped to the rectangle of pixels originating at (sx, sy) with width sw, and height sh.
  • {{domxref("WorkerGlobalScope.dump()")}} {{deprecated_inline}} {{non-standard_inline}}
    • : Allows you to write a message to stdout — i.e., in your terminal. This is the same as Firefox's {{domxref("window.dump")}}, but for workers.
  • {{domxref("WorkerGlobalScope.fetch()")}}
    • : Starts the process of fetching a resource from the network.
  • {{domxref("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');.
  • {{domxref("WorkerGlobalScope.queueMicrotask()")}}
    • : Queues a microtask to be executed at a safe time prior to control returning to the browser's event loop.
  • {{domxref("WorkerGlobalScope.setInterval()")}}
    • : Schedules a function to execute every time a given number of milliseconds elapses.
  • {{domxref("WorkerGlobalScope.setTimeout()")}}
    • : Schedules a function to execute in a given amount of time.
  • {{domxref("WorkerGlobalScope.structuredClone()")}}
  • {{domxref("WorkerGlobalScope.reportError()")}}
    • : Reports an error in a script, emulating an unhandled exception.

Events

  • {{domxref("WorkerGlobalScope/error_event", "error")}}
    • : Fired when an error occurred.
  • {{domxref("WorkerGlobalScope/languagechange_event", "languagechange")}}
    • : Fired at the global/worker scope object when the user's preferred languages change.
  • {{domxref("WorkerGlobalScope/offline_event", "offline")}}
    • : Fired when the browser has lost access to the network and the value of navigator.onLine switched to false.
  • {{domxref("WorkerGlobalScope/online_event", "online")}}
    • : Fired when the browser has gained access to the network and the value of navigator.onLine switched to true.
  • {{domxref("WorkerGlobalScope/rejectionhandled_event", "rejectionhandled")}}
    • : Fired on handled {{jsxref("Promise")}} rejection events.
  • {{domxref("WorkerGlobalScope/securitypolicyviolation_event", "securitypolicyviolation")}}
  • {{domxref("WorkerGlobalScope/unhandledrejection_event", "unhandledrejection")}}
    • : Fired on unhandled {{jsxref("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 {{domxref("DedicatedWorkerGlobalScope")}} and {{domxref("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 ({{domxref("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

{{Specifications}}

Browser compatibility

{{Compat}}

See also

  • Other global object interface: {{domxref("Window")}}, {{domxref("DedicatedWorkerGlobalScope")}}, {{domxref("SharedWorkerGlobalScope")}}, {{domxref("ServiceWorkerGlobalScope")}}
  • Other Worker-related interfaces: {{domxref("Worker")}}, {{domxref("WorkerLocation")}} and {{domxref("WorkerNavigator")}}
  • Using web workers