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    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.

    Properties

    This interface inherits properties from the EventTarget interface and implements properties from WindowTimers, WindowBase64, and WindowEventHandlers.

    Standard properties

    WorkerGlobalScope.caches Read only
    Returns the CacheStorage object associated with the current context. This object enables service worker functionality such as storing assets for offline use, and generating custom responses to requests.
    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 DedicatedWorkerGlobalScopeSharedWorkerGlobalScope 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.

    Event Handlers

    This interface inherits event handlers from the EventTarget interface and implements event handlers from WindowTimers, and WindowBase64.

    WorkerGlobalScope.onerror
    Is an EventHandler representing the code to be called when the error event is raised.
    WorkerGlobalScope.onoffline
    Is an EventHandler representing the code to be called when the offline event is raised.
    WorkerGlobalScope.ononline
    Is an EventHandler representing the code to be called when the online event is raised.
    WorkerGlobalScope.onlanguagechange
    An EventHandler fired at the global/worker scope object when the user's preferred languages change.
    WorkerGlobalScope.onclose
    Is an EventHandler representing the code to be called when the close event is raised.

    Methods

    This interface inherits methods from the EventTarget interface and implements methods from WindowTimers, WindowBase64, WindowEventHandlers, and GlobalFetch.

    Standard methods

    WorkerGlobalScope.close()
    Discards any tasks queued in the WorkerGlobalScope's event loop, effectively closing this particular scope.
    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

    WindowBase64.atob()
    Decodes a string of data which has been encoded using base-64 encoding.
    WindowBase64.btoa()
    Creates a base-64 encoded ASCII string from a string of binary data.
    WindowTimers.clearInterval()
    Cancels the repeated execution set using WindowTimers.setInterval().
    WindowTimers.clearTimeout()
    Cancels the repeated execution set using WindowTimers.setTimeout().
    GlobalFetch.fetch()
    Starts the process of fetching a resource.
    WindowTimers.setInterval()
    Schedules the execution of a function each X milliseconds.
    WindowTimers.setTimeout()
    Sets a delay for executing a function.

    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);

    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 Status Comment
    WHATWG HTML Living Standard
    The definition of 'WorkerGlobalScope' in that specification.
    Living Standard No change from Web Workers.
    Web Workers
    The definition of 'WorkerGlobalScope' in that specification.
    Candidate Recommendation Initial definition.
    Service Workers Editor's Draft Defines caches.

    Browser compatibility

    Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
    Basic support 4 3.5 (1.9.1) 10 10.6 4
    ononline, onoffline (Yes) 29 (29) ? ? ?
    console (Yes) 29 (29) as  WorkerConsole
    30 (30) as the regular Console
    ? ? ?
    performance (Yes) 34 (34) ? ? ?
    caches 40 ? Not supported ? Not supported
    Feature Android Chrome for Android Firefox Mobile (Gecko) Firefox OS (Gecko) IE Mobile Opera Mobile Safari Mobile
    Basic support ? (Yes) 1.0 (1.9.1) 1.0.1 10 11.5 5.1
    ononline, onoffline ? (Yes) 29.0 (29) as a specific WorkerConsole
    30.0 (30) as the regular Console
    1.4 ? ? ?
    console ? (Yes) 29.0 (29) 1.4 ? ? ?
    performance ? (Yes) 34.0 (34) 2.1 ? ? ?
    caches (Yes) (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

    See also

    Document Tags and Contributors

    Contributors to this page: chrisdavidmills, teoli
    Last updated by: chrisdavidmills,