HTML5 HTML5 Web Workers

Question 1

What is the primary purpose of HTML5 Web Workers?

Accepted Answer

To run JavaScript in a background thread without blocking the main UI thread

Answer

To load external CSS stylesheets asynchronously

Answer

To create animated graphics on a canvas element

Answer

To store large amounts of data in the browser cache

Question 2

Which of the following correctly creates a new Web Worker?

Accepted Answer

var worker = new Worker('worker.js');

Answer

var worker = Worker.create('worker.js');

Answer

var worker = new Thread('worker.js');

Answer

var worker = document.createWorker('worker.js');

Question 3

How does the main thread send a message to a Web Worker?

Accepted Answer

worker.postMessage(data)

Answer

worker.sendMessage(data)

Answer

worker.emit('message', data)

Answer

worker.dispatch(data)

Question 4

Inside a Web Worker, which global object is available instead of 'window'?

Accepted Answer

self

Answer

global

Answer

worker

Answer

context

Question 5

Which of the following resources is NOT accessible inside a Web Worker?

Accepted Answer

The DOM (document object)

Answer

The XMLHttpRequest object

Answer

The navigator object

Answer

The setTimeout function

Question 6

How do you terminate a Web Worker from the main thread?

Accepted Answer

worker.terminate()

Answer

worker.stop()

Answer

worker.kill()

Answer

worker.close()

Question 7

Which event listener is used in the main thread to receive messages from a Web Worker?

Accepted Answer

worker.onmessage

Answer

worker.onreceive

Answer

worker.onresponse

Answer

worker.ondata