Web Workers API support in Opera Presto 2.11

W3C reference:

W3C Web Workers API

Opera article

Web Workers rise up!

Opera Presto offers support for Web Workers, an API for running scripts in the background independently of any user interface scripts. This allows for long-running scripts that are not interrupted by scripts that respond to clicks or other user interactions, and allows long tasks to be executed without yielding to keep the page responsive. See this demo

Infrastructure

Workers

There are two kinds of workers; dedicated workers, and shared workers.

Dedicated workers

Once created, they are linked to their creator. Message ports can be used to communicate from a dedicated worker to multiple other browsing contexts or workers.

Shared workers

Are named, and once created, any script running in the same origin can obtain a reference to that worker and communicate with it.

Global scope

The global scope is the "inside" of a worker.

Interface support

WorkerGlobalScope abstract interface

Interface	Attributes	Description	Support
WorkerGlobalScope
	self	This attribute must return the WorkerGlobalScope object itself.	Yes
	location	This attribute must return the WorkerLocation object created for the WorkerGlobalScope object when the worker was created. It represents the absolute URL of the script that was used to initialize the worker, after any redirects.	Yes

Method	Attributes	Description	Support
initErrorEvent()	message	This attribute represents the error message.	Yes
	filename	This attribute represents the absolute URL of the script in which the error originally occurred.	Yes
	lineno	This attribute represents the line number where the error occurred in the script.	Yes

Event handler	Event handler event type	Support
onerror	error	Yes

DedicatedWorkerGlobalScope interface

Interface	Method	Description	Support
DedicatedWorkerGlobalScope
	postMessage()	This method must act as if, when invoked, it immediately invoked the method of the same name on the port, with the same arguments, and returned the same return value.	Yes

Event handler	Event handler event type	Support
onmessage	message	Yes

SharedWorkerGlobalScope interface

Interface	Attribute	Description	Support
SharedWorkerGlobalScope
	name	This attribute must return the value it was assigned when the SharedWorkerGlobalScope object was created by the "run a worker" algorithm. Its value represents the name that can be used to obtain a reference to the worker using the SharedWorker constructor.	Yes

Event handler	Event handler event type	Support
onconnect	connect	Yes

AbstractWorker abstract interface

Event handler	Event handler event type	Support
onerror	error	Yes

Worker interface

Interface	Methods	Description	Support
Worker
	terminate()	This method, when invoked, must cause the "terminate a worker" algorithm to be run on the worker with the object that is associated.	Yes
	postMessage()	This method on Worker objects must act as if, when invoked, it immediately invoked the method of the same name on the port, with the same arguments, and returned the same return value.	Yes

Event handler	Event handler event type	Support
onmessage	message	Yes

SharedWorker interface

Interface	Attribute	Description	Support
SharedWorker
	port	This attribute must return the value it was assigned by the object's constructor. It represents the MessagePort for communicating with the shared worker.	Yes

APIs available to workers

WorkerUtils interface

Interface	Attribute	Description	Support
WorkerUtils
	WorkerNavigator	This attribute represents the identity and state of the user agent (the client).	Yes
	navigator	Ths attribute returns an instance of the WorkerNavigator interface.	Yes