Javascript

Question 1

Outline the differences between client-side scripting and server-side scripting.

Answer 1

Client Side:
-HTML, CSS, Javascript used
-Source code visible to User
-No security for data
-Main function to provide the requested output.
-Depends on browser and verison
-Runs on user’s computer

Server-Side Scripting
-PHP, Python, Javascript etc.
-Source code invisible
-More security
-Main function to provide access to database as per request.
-Does not depend on the browser
-Runs on the web server

Question 2

Who designed Javascript? Working for who? When? How long did it take?

Answer 2

Brendan Eich
Netscape
1995
10 days

Question 3

When did Javascript become an ECMA standard?

Answer 3

1997

Question 4

What does ECMA stand for?

Answer 4

European Computer Manufacturers Association.

Question 5

Outline the key differences between JAVA and javascript.

Answer 5

JAVA:
compiled
back-end
Strong security
C++ syntax
Requires JAVA development kit
For various apps

Javascript:
Interpreted
Front-end
Weak security
C syntax
Written in any text editor
Mainly for web apps

Question 6

What are the three approaches for adding Javascript to a HTML file?

Answer 6

External .js file
Internal between

 tag
Inline javascript handles directly within HTML

Question 7

What is the pros and cons of internal javascript?

Answer 7

Pros: Fast to implement
Easy to Read Code

Cons:
Makes it hard to reuse code.
Slows Performance.

Question 8

What are the pros and cons of inline javascript?

Answer 8

Pros: Quick to implement
Perfect for a small app

Cons: The code is not reusable.
Slows performance
Code readability concerns

Question 9

What function is used to select HTML elements by id?

Answer 9

getElementById((“id”)

Question 10

What function adds an element to the end of an array and what function adds an element to the start of the array?

Answer 10

push(element to be added)
unshift(element to be added)

Question 11

What function removes (a) the last element of an array and (b) the first element of an array and returns that element?

Answer 11

pop()
shift()

Question 12

When are backticks used in javascript?

Answer 12

When you want to include a variable value in the print statement of a string.

Question 13

Equality and non-equality symbols for javascript.

Answer 13

Equality: ===
Non-equality: !==

Question 14

Syntax for an arrow function.

Answer 14

let function_name = (argument1, argument2,..) => expression

Question 15

What is an event in javascript?

Answer 15

Events are things that happen in the system you are programming, which the system tells you about so your code can react to them.

Question 16

What are event handlers?

Answer 16

Run when an event fires allowing web pages to respond appropriately to change.

Question 17

What must be done if Javascript is loaded and parsed before HTML but we want to alter HTML? 2 solutions.

Answer 17

document.addEventListener(“DOMContentLoaded”, function(event){
//add further javascript
});

Question 18

How is local vs global scope define in javascript?

Answer 18

Local scope is inside {}

Question 19

What is the TDZ in javascript?

Answer 19

Temporal Dead Zone
Is a phase in the execution of JavaScript code when a variable is in a state of “limbo”. During this phase, the variable exists, but you cannot access its value.

Question 20

What does NaN stand for? What is it?

Answer 20

Not a Number
Represent an undefined or unrepresentable result of a mathematical operation.

Question 21

What is an API?

Answer 21

Application Programming Interfaces are ready-made sets of code building blocks that allow a developer to implement programs that would otherwise be harder to implement.