Javascript / JQuery / OOP / JSON (junior)

Question 1

What is a variable?

Answer 1

Where data can be stored!

Question 2

Why are variables useful?

Answer 2

variable can be used to store and recall information through-out a program.

Question 3

What two special characters can a variable begin with?

Answer 3

$ _

Question 4

How do you declare a variable?

Answer 4

using a variable identifier

Question 5

How do you assign a value to a variable?

Answer 5

= next to variable name

Question 6

Are variables case sensitive?

Answer 6

yes

Question 7

Which words cannot be used as variable names?

Answer 7

keywords (var, function, if) numbers..

Question 8

What is a string?

Answer 8

Sub-series of characters that comes inside two ‘ or “

Question 9

What is the string concatenation operator?

Answer 9

+

Question 10

What is the difference when it comes to using single quotes or double quotes ( ‘ ‘ or “ “ )?

Answer 10

no difference in functionality

Question 11

How do you escape quotation characters?

Answer 11

\ before the quote.

Question 12

What is a number in JavaScript?

Answer 12

an integer

Question 13

What is an arithmetic operator?

Answer 13

Mathematical function that takes two operands and performs a calculation on them.

Question 14

Name four of the arithmetic operators?

Answer 14

add subtract

Question 15

What is the order of execution?

Answer 15

PEMDAS

Question 16

What is a boolean?

Answer 16

true / false

Question 17

What is a comparison operator?

Answer 17

< = >

Question 18

What is a comparison operator?

Answer 18

< = > == ===

Question 19

What is a function?

Answer 19

Series of statements that are grouped together because they perform a specific task.

Question 20

Why are functions useful?

Answer 20

you can reuse the function (rather than repeating the same set of statements).

Question 21

How do you call a function?

Answer 21

function name followed by () with any argument inside.

Question 22

What are the parts of a function definition?

Answer 22

function keyword, function name and code bloke inside curly braces.

Question 23

What is the difference between a parameter and an argument?

Answer 23

methods are same as functions, except they’re created inside (and are part of) an object.

Question 24

What is the difference between a parameter and an argument?

Answer 24

parameters are placeholders for values in function and arguments are the values when calling the function.

Question 25

Why is it important to understand truthy and falsy values?

Answer 25

They allow decision making

Question 26

Why is the typeof an object null?

Answer 26

it's a bug!

Question 27

What is the difference between null and undefined?

Answer 27

an undefined variable has no value, null has no specific value assigned to it but has a placeholder and act as an object ready to be assigned with a value.

Question 28

What is the proper syntax for using the or operator?

Answer 28

|| double pipe

Question 29

Why do you want to avoid using == for comparison?

Answer 29

== doesn't check on type similarity!

Question 30

Do all if statements require an else statement?

Answer 30

no

Question 31

What is the primary use case for switches?

Answer 31

comparing any individual value against a range of other individual values.

Question 32

Does the default case have to be at the bottom of the switch statement?

Answer 32

to get executed after checking for all possible cases

Question 33

Does the default case have to be at the bottom of the switch statement?

Answer 33

no!

Question 34

What is an object in JavaScript?

Answer 34

A set of variables and functions grouped together.

Question 35

How do you create an object literal?

Answer 35

declaring a variable with a name for object, equal sign, curly braces and key/value for each property or method in between separated by comma

Question 36

What is a property in relation to JavaScript objects?

Answer 36

A set of key and value.

Question 37

When should you use bracket notation over dot notation with objects?

Answer 37

any time there's illegal property name dot notation needs to be used to access the value

Question 38

How do you remove a property from an object?

Answer 38

delete operator.

Question 39

What is an array in JavaScript?

Answer 39

list of data

Question 40

How do you create an array literal?

Answer 40

assigning data in brackets

Question 41

What are the keys for the values inside an array?

Answer 41

index numbers.

Question 42

Arrays have a property named length. Because arrays have a properties, what other data structure are they similar to?

Answer 42

objects

Question 43

What are some good use cases for using objects inside arrays?

Answer 43

online shopping card with list of items and their properties (price, ..)

Question 44

What is the primary advantage to storing your selected elements in a variable?

Answer 44

so they can be reused every time without a need to target them again

Question 45

Why might you need JavaScript to modify the DOM after the page loads?

Answer 45

adjustments and updates based on user behavior

Question 46

How can you better prepare when writing HTML for DOM manipulation in your JavaScript code?

Answer 46

setting better structure and placement for items that are going to be manipulated

Question 47

What are the differences between innertext and textContent?

Answer 47

textContent gets the content of all elements, including and