Basics

Question 1

What are variables?

Answer 1

Variables are “data buckets” to store a value for later

Question 2

What are the 2 part of a variable?

Answer 2

Let age = 25

Declaration: Let age
Assignment: age = 25

Question 3

What are the function of a declaration and assignment?

Answer 3

A declaration create a “bucket” to store some data

An assignment is the step of putting something into the “bucket”

Question 4

What can you store in variables?

Answer 4

Strings
Numbers
Booleans

Question 5

What are Booleans data types?

Answer 5

Data with True and False values

Question 6

What are strings?

Answer 6

Strings are used to store text and are surrounded by quotes e.g “10283”

Question 7

Differences between numbers integer and floated value?

Answer 7

Int = 29
Float = 5.14876

can also be signed

Int = +29
Float = -10.375

Question 8

JS can also do arithmetic, what sign are used?

Answer 8

\+ addition
- subtraction
* multiplication 
/ Division
% Modulus

Question 9

What is 10 % 6?

Answer 9

Modulus gives us the remaining so it is 4

Question 10

let imputinterval = document.querySelector(“dancedancerevolution”).value

How can this code be read?

Answer 10

This line looks at the document and select the value present in the HTML document with id of dancedancerevolution and store it in the value imputinterval

Question 11

How can this code be read?

h1holder.addeventlistener(“click”, sum)

Answer 11

We add an “eventlistener” into the “h1holder” where if you click on the h1holder it will run the function “sum”

Question 12

What are the logical operators in JS?

Answer 12

== equal to (value )(x = = 8)
=== equal to (value and type) (x = = = "3")
!= not equal (value)(x != 8)
!== not equal (value and type) (x!== "3")
> greater than
< less than
>= greater or equal
<= less or equal

Question 13

How do you write a conditional syntax?

Answer 13

if(condition is true) {
  //Do this
}else if(condition is true){
  //Do this
}else{
  //default stuff
}

Question 14

How do you write multiple conditions?

Answer 14

if (name===”leon” && status === “ballin”) {
…
}

Question 15

Can you write multiple condition with or?

Answer 15

Yes you use this symbol “||”
E.g

if (day === “monday” || day === “sunday”){
…
}

Question 16

How do you add a button to perform an action upon clicking?

Answer 16

document.querySelector(#id).addevEntListener(“click”, stopSnacking)

Question 17

How to get an input from a document?

Answer 17

let numOfSnakcs = document.querySelector(“input”).value

Question 18

How to make sure an input is a number?

Answer 18

wrap the code into “number” eg.

Number(document.querySelector(“input”).value)

Question 19

Create a function that takes in a word and a number. Console log the word x times where x was the number passed in

Answer 19

function wordXTimes(word, num){
  for(let i = 1; i <= num; i++){
     console.log(word)
    }
}

wordXTimes(“wonderful”, “21”)

Question 20

What are the 8 data type in JS?

Answer 20

There are 8 basic data types in JavaScript.

• number: integer or floating-point.
• bigint: is for integer numbers of arbitrary length.
• string: A string may have zero or more characters
• boolean: true/false.
• null: for unknown values – a standalone type that has a single value null.
• undefined: for unassigned values – a standalone type that has a single value undefined.
• object: for more complex data structures.
• symbol: for unique identifiers.

Question 21

What is alert for?

Answer 21

It is a built in function in JS that shows a message in the browser and waits for the user to press ok

Question 22

What are some built in function in JS to allow to interact with the user?

Answer 22

• alert
• prompt
• confirm

Question 23

How do you concatenate strings?

Answer 23

With the + operator

“My” + “name”

Question 24

How can i = i + 1 be also written?

Answer 24

i++

Question 25

How can you do both a mathematical operation and assignment in one step.

Answer 25

You can use the “+=” or “-=” operator

This add operator add a value to the variable and reassign the new value to the variable

Question 26

Difference between Assignment and Comparisons

Answer 26

Assignment is done with = (one equal sign)

Comparison is done with ==/=== (2 or 3 equal signs)

Question 27

How do you alert a certain character in a string?

Answer 27

Strings can be seen as arrays and a similar syntax can be used. For example in the following string:

let str = ‘hello twitch!’

to alert the 3rd character we can code it in these different ways:

1) alert( srt [2] )
2) alert ( str.charAt(2) )

Question 28

How to make sure a string is all upper case?

Answer 28

.toUpperCase

Question 29

What is the “Math.” method?

Answer 29

Is a built-in object that has properties and methods for mathematical constants and functions.

Question 30

How can you put a variable into a string?

Answer 30

It can be done by using “${…}”

Question 31

What does the method ‘Math.random’ do?

Answer 31

It returns a number between 0 and 1

Question 32

What are API?

Answer 32

• API are a simple interface to do something complex

- Let one thing communicate with another thing without having to know how things are implemented

Question 33

Why API can be seen as a restaurant menu?

Answer 33

Because it is a simple interface that let us interact with the kitchen even though we don’t know how to make the dishes in the menu

Question 34

What does API stand for?

Answer 34

Application Programming Interface

Question 35

What are back ticks quote `` for?

Answer 35

They are extended functionality quotes that allows to insert variables into strings using ${…}