1. Intro - Part A

Question 1

What is JS?

2x

Answer 1

Created to “make web pages come alive”

Programs are called “scripts”

Question 2

How is JS code provided and executed?

3x

Answer 2

Can be written in a web page’s HTML
Runs automatically as page loads
As plain text - no special preparation or compilation needed to run

Question 3

Where is JS code executed?

3x

Answer 3

Browser
Server
Any device that has JS engine

Question 4

What is a JavaScript engine?

Answer 4

Special program for enabling JS to be executed

Question 5

What is the JavaScript engine embedded in the browser sometimes called?

Answer 5

JavaScript virtual machine

Question 6

Give codenames for commonly used browser engines

5 x

Answer 6

Chrome, Opera: V8
Firefox: SpiderMonkey
IE: Trident, Chakra
Edge: ChakraCore
Safari: Nitro, SquirrelFish

Question 7

Summarise how engines work

3x

Answer 7

1. Reads (parses) the script
2. Converts (compiles) the script to machine language
3. Machine code runs at a fast speed

Question 8

What takes place at each stage of engine’s process?

2x

Answer 8

Optimisations

Analyses data flowing through script to further optimise machine code

Question 9

What can in-browser JS do?

3x

Answer 9

Everything to do with:
Webpage manipulation
Interaction with the user
Interaction with the webserver

Question 10

Give examples of in-browser JS actions

5x

Answer 10

Add to / amend page content, modify styles
React to user actions: mouse clicks, pointer movements, key presses
Send requests over network to remote servers, download/upload files (AJAX & COMET technologies)
Get and set cookies, show messages and ask questions to the visitor
Remember data on client-side (local storage)