LearningFuze Mod 1 - Javascript

Question 1

What is the purpose of variables?

Answer 1

Variables are used to store information to be referenced and manipulated in a computer program.

Question 2

How do you declare a variable?

Answer 2

assigning it with a value

Question 3

How do you initialize (assign a value to) a variable?

Answer 3

by adding an equals (assignment operator) to the var

Ex (var=””)

Question 4

What characters are allowed in variable names?

Answer 4

a letter a dollar sign $ or an underscore (_) or numbers but they CANNOT be in the start

Question 5

What does it mean to say that variable names are “case sensitive”?

Answer 5

It relies on camelCase

Question 6

What is the purpose of a string?

Answer 6

The String object is used to represent and manipulate a sequence of characters.

Question 7

What is the purpose of a number?

Answer 7

Store numeric value

Question 8

What is the purpose of a boolean?

Answer 8

it creates true or false statements

Question 9

What does the = operator mean in JavaScript?

Answer 9

it assigns value

Question 10

How do you update the value of a variable?

Answer 10

We write the variable name and giving a new value would change it

Question 11

What is the difference between null and undefined?

Answer 11

undefined is a type by itself (undefined). … Here as the variable is declared but not assigned to any value, the variable by default is assigned a value of undefined. On the other hand, null is an object. It can be assigned to a variable as a representation of no value.

Question 12

Why is it a good habit to include “labels” when you log values to the browser console?

Answer 12

Because if you do not assign a value it will make a global value and it can break it

Question 13

Give five examples of JavaScript primitives.

Answer 13

undefined , null , boolean , string and number

Question 14

What data type is returned by an arithmetic operation?

Answer 14

returns a single numerical value.

Question 15

What is string concatenation?

Answer 15

joining two or more strings together to make one

Question 16

What purpose(s) does the + plus operator serve in JavaScript?

Answer 16

It combines two strings and does addition

Question 17

What data type is returned by comparing two values (

Answer 17

boolean, which is true or false statements

Question 18

What does the += “plus-equals” operator do?

Answer 18

adds the value of the right operand to a variable and assigns the result to the variable.

Question 19

What are objects used for?

Answer 19

Its used to model

Question 20

What are object properties?

Answer 20

Is a variable

Question 21

Describe object literal notation.

Answer 21

NEEDED

Question 22

What are the two ways to get or update the value of a property?

Answer 22

.notion or bracket notion

Question 23

What are arrays used for?

Answer 23

To store values

Question 24

How are arrays different from “plain” objects?

Answer 24

They are numerical index

Question 25

Describe array literal notation.

Answer 25

NEEDED

Question 26

What is the length property of an array?

Answer 26

it records the values in the array

Question 27

How do you calculate the last index of an array?

Answer 27

length of the array -1

Question 28

What is a function in JavaScript?

Answer 28

Block of code and call as needed

Question 29

Describe the parts of a function definition.

Answer 29

The function keyword, optional name, the perimeter list and the end of the code block

Question 30

Describe the parts of a function call.

Answer 30

to call, we use the name (if it has one) and the parentheses

Question 31

When comparing them side-by-side, what are the differences between a function call and a function definition?

Answer 31

NEEDED

Question 32

What is the difference between a parameter and an argument?

Answer 32

NEEDED

Question 33

Why are function parameters useful?

Answer 33

Stores data so the function can use

Question 34

What two effects does a return statement have on the behavior of a function?

Answer 34

NEEDED

Question 35

Why do we log things to the console?

Answer 35

To show the output in our javascript

Question 36

What is a method?

Answer 36

A method is a function which is a property of an object.

Question 37

How is a method different from any other function?

Answer 37

a method is associated with an object

Question 38

How do you remove the last element from an array?

Answer 38

by using the pop method

Question 39

How do you round a number down to the nearest integer?

Answer 39

by using the math.floor() method

Question 40

How do you generate a random number?

Answer 40

by using .random() method

Question 41

How do you delete an element from an array?

Answer 41

the pop method, shift method or the splice method

Question 42

How do you append an element to an array?

Answer 42

the .push() method appends and the unshift method prepends it

Question 43

Do string methods change the original string? How would you check if you weren't sure?

Answer 43

No it will not change the original string and you can check it with the console log

Question 44

Roughly how many string methods are there according to the MDN Web docs?

Answer 44

Around 30+

Question 45

Is the return value of a function or method useful in every situation?

Answer 45

No

Question 46

Roughly how many array methods are there according to the MDN Web docs?

Answer 46

Around 30+

Question 47

What three-letter acronym should you always include in your Google search about a JavaScript method or CSS property?

Answer 47

MDN

Question 48

Give 6 examples of comparison operators.

Answer 48

== is equal to, != is not equal to, > greater than, < less than, >= greater than or equal to, <= less than or equal to

Question 49

What data type do comparison expressions evaluate to?

Answer 49

Boolean

Question 50

What is the purpose of an if statement?

Answer 50

it makes checks on functions to do a certain action

Question 51

What are the three logical operators?

Answer 51

&& logical and, || logical or, ! logical not

Question 52

Describe the syntax (structure) of an if statement.

Answer 52

NEEDED

Question 53

What is the purpose of a loop?

Answer 53

Run a block of code until a certain amount of time or the condition is met

Question 54

What is the purpose of a condition expression in a loop?

Answer 54

the last thing we do before we start the code thats inside of the loop

Question 55

What does "iteration" mean in the context of loops?

Answer 55

It's the process of repeating the loop

Question 56

When does the condition expression of a while loop get evaluated?

Answer 56

It's before each time and after each iteration

Question 57

When does the initialization expression of a for loop get evaluated?

Answer 57

One time before the loop begins

Question 58

When does the condition expression of a for loop get evaluated?

Answer 58

Before each iteration

Question 59

When does the final expression of a for loop get evaluated?

Answer 59

After the work of the conditional expression

Question 60

Besides a return statement, which exits its entire function block, which keyword exits a loop before its condition expression evaluates to false?

Answer 60

break; would be the keyword

Question 61

What does the ++ increment operator do?

Answer 61

It increments by 1

Question 62

How do you iterate through the keys of an object?

Answer 62

with a for in loop

Question 63

What event is fired when a user places their cursor in a form control?

Answer 63

focus event

Question 64

What event is fired when a user's cursor leaves a form control?

Answer 64

blur event

Question 65

What event is fired as a user changes the value of a form control?

Answer 65

Input event

Question 66

What event is fired when a user clicks the "submit" button within a ?

Answer 66

submit event

Question 67

What does the event.preventDefault() method do?

Answer 67

Cancels the event if its cancelable

Question 68

What does submitting a form without event.preventDefault() do?

Answer 68

Submits it back to the page

Question 69

What property of a form control object gets and sets its value?

Answer 69

Value property

Question 70

What is one risk of writing a lot of code without checking to see if it works so far?

Answer 70

You can have an error in your code and you will have to dig to see what is wrong with it.

Question 71

What is an advantage of having your console open when writing a JavaScript program?

Answer 71

Its useful to see if you are getting error messages