Functions and classes available to Web Workers
In addition to the standard JavaScript set of functions (such as String, Array, Object, JSON, etc.), there are a variety of functions available from the DOM to workers. This article provides a list of those.
Worker Contexts & Functions
Workers run in a different global context than the current window! While Window is not directly available to workers, many of the same methods are defined in a shared mixin (WindowOrWorkerGlobalScope), and made available to workers through their own WorkerGlobalScope-derived contexts:
DedicatedWorkerGlobalScopefor dedicated workersSharedWorkerGlobalScopefor shared workersServiceWorkerGlobalScopefor service workers
Some of the functions that are common to all workers and to the main thread (from WindowOrWorkerGlobalScope) are: atob(), btoa(), clearInterval(), clearTimeout(), dump()
Non-standard
, setInterval(), setTimeout().
The following functions are only available to workers:
WorkerGlobalScope.importScripts()(all workers),DedicatedWorkerGlobalScope.postMessage(dedicated workers only).
Web APIs available in workers
Note: If a listed API is supported by a platform in a particular version, then it can generally be assumed to work in web workers.
The following Web APIs are available to workers:
Broadcast Channel APICache APIChannel Messaging APIConsole APICryptoCustomEvent,DOMRequestandDOMCursorFetchFileReaderFileReaderSync(only works in workers!)FormDataImageDataIndexedDB- Media Source Extensions API (dedicated workers only)
- Network Information API
NotificationsPerformancePerformanceEntryPerformanceMeasurePerformanceMarkPerformanceObserverPerformanceResourceTimingPromise- Server-sent events
ServiceWorkerRegistrationTextEncoderandTextDecoderURL- WebGL with
OffscreenCanvas WebSocketXMLHttpRequest(although theresponseXMLandchannelattributes are always null).
Workers can also spawn other workers, so these APIs are also available: