WorkerGlobalScope
Summary
An object representing the “inside” of a worker.
Properties
- location
- Returns the WorkerLocation object created for the WorkerGlobalScope object when the worker was created.
- navigator
- Returns an instance of the WorkerNavigator interface, which represents the identity and state of the user agent (the client).
- onerror
- An event listener to be called when an error occurs.
- onoffline
- An event listener to be called when the worker goes offline.
- ononline
- An event listener to be called when the worker goes online.
- self
- Returns the WorkerGlobalScope object.
Methods
- close
- Discards any pending tasks and immediately closes the worker.
- importScripts
- Fetches one or more script resources, identified by absolute URLs.
Events
No events.
Notes
The WorkerGlobalScope object is accessed by using the self or this property and is accessed only inside a worker. A worker has the following functionality within its scope:
- It can use the XMLHttpRequest method.
- It has a self property, which contains a reference to the worker object.
- It can call all global JavaScript core methods.
- It has a navigator object, which provides the appName, appVersion, onLine, userAgent, and platform properties but no others.
- The location property creates the WorkerLocation object, which contains URL information on the worker’s location. This property is similar to the Window.location property, but is read-only.
- It supports the worker versions of the setTimeout, setInterval, clearTimeout, and clearInterval methods, which are similar to the methods of the same name for the Window object.
- It can load other JavaScript files into the scope of the worker using the importScripts method.
Workers do not have access to the Document Object Model (DOM), nor the window, document, and parent objects. To terminate a worker thread from inside, use the close method. From the main document, use the terminate method to terminate the worker thread. You can send messages to the main document using postMessage and receive messages from the main document using the onmessage message handler. You can create new child workers from inside a worker. They must all run in the same host and their location depends on the parent worker of the new worker, not the original webpage. Because a new worker is likely to be in a separate process, you shouldn’t create too many workers at once. Also, because messages between workers and their parents are copies and not shared, too many workers can use up resources quickly.
Related specifications
- W3C Web Workers Specification
- W3C Editor’s Draft
Attributions
Microsoft Developer Network: Windows Internet Explorer API reference Article