HTML5 HTML5 Web Workers 2

Question 1

What is a Shared Worker in HTML5, and how does it differ from a Dedicated Worker?

Accepted Answer

A Shared Worker can be accessed by multiple scripts from different windows or tabs of the same origin

Answer

A Shared Worker runs on the server rather than the client

Answer

A Shared Worker has access to the DOM, unlike a Dedicated Worker

Answer

A Shared Worker automatically syncs data between browser tabs using localStorage

Question 2

Which event fires on the main thread when a Web Worker encounters an uncaught error?

Accepted Answer

onerror

Answer

onfail

Answer

onexception

Answer

oncatch

Question 3

What function is used to import external scripts inside a Web Worker?

Accepted Answer

importScripts('script.js')

Answer

require('script.js')

Answer

import 'script.js'

Answer

load('script.js')

Question 4

What is the key advantage of using Transferable Objects with postMessage() in Web Workers?

Accepted Answer

The data is transferred by reference (zero-copy), making it much faster for large data like ArrayBuffers

Answer

Transferable Objects allow workers to directly access the DOM

Answer

They enable workers to communicate with external servers without CORS restrictions

Answer

They compress data automatically before transferring to reduce memory usage

Question 5

Which Web Worker type is specifically designed to act as a network proxy and enable offline capabilities?

Accepted Answer

Service Worker

Answer

Shared Worker

Answer

Dedicated Worker

Answer

Background Worker

Question 6

How do you safely close a Web Worker from within the worker script itself?

Accepted Answer

self.close()

Answer

self.terminate()

Answer

self.exit()

Answer

self.stop()

Question 7

What does the 'message' event's 'data' property contain when received in a Web Worker?

Accepted Answer

The value passed to postMessage() by the sender, structured-cloned

Answer

A reference to the main thread's window object

Answer

The origin URL of the page that created the worker

Answer

A stream object for reading large payloads