JavaScript - Basics

Question 1

ECMA Script is

Answer 1

The standard for javascript

Question 2

A variable is not a value, but …

Answer 2

it points to a value

Question 3

When naming a variable, it must start with…

Answer 3

a letter

Question 4

When creating a variable we use the case convention called

Answer 4

camelCase

Question 5

The difference between let and const is…

Answer 5

let creates variables that can have the value reassigned, const for the variables that shouldn’t be reassigned

Question 6

The two categories of data types are

Answer 6

Primitives (immutable) and non-primitives (mutable)

Question 7

The 7 primitive data types are:

Answer 7

string, number, bigint, boolean, undefined, null and symbol

Question 8

The non-primitive data type is:

Answer 8

objects

Question 9

If… else and switch statements are:

Answer 9

conditional statements

Question 10

&& means

Answer 10

and

Question 11

|| means

Answer 11

or

Question 12

What is the syntax of a ternary operator?

Answer 12

condition ? return if condition is true : return if condition is false

Question 13

A function is

Answer 13

a block of code that can be reused

Question 14

What’s the difference between parameters and arguments?

Answer 14

parameters are defined when we create the function, arguments is the value we pass when calling the function

Question 15

The return statement will

Answer 15

stop the execution of the function and give a value in return

Question 16

How do I access the first element of const myArr = [“Ana”, 32, true]

Answer 16

myArr[0]

Question 17

How do I check the length of the array const myArr = [“Ana”, 32, true]

Answer 17

myArr.length

Question 18

What is a higher order function?

Answer 18

a function that accepts another function as the argument

Question 19

What is a callback function?

Answer 19

a function that is passed as the argument to another function (a higher order function)

Question 20

Are arrays a data structure?

Answer 20

Yes

Question 21

When creating a for loop, what are the 3 statements necessary?

Answer 21

initial value, condition to meet, what to do after each loop

Question 22

What’s the difference between a while loop and a do while loop?

Answer 22

the while loop will always check the condition first and only run if condition is met, the do while loop will run the code once, then check the condition on the following loop

Question 23

If a condition of a loop is never met, what happens?

Answer 23

We create an infinite loop

Question 24

What does DOM stands for

Answer 24

Document Object Model

Question 25

If I want to target something by its ID, which method do we use?

Answer 25

document.getElementById(“idToTarget”)

Question 26

What happens when we use the innerHTML property?

Answer 26

we have access the content of a node element

Question 27

How can we create new HTML elements?

Answer 27

document.createElement(‘elementTag’)

Question 28

What is the spead operator used for?
const numbersArray = [1, 2, 3]

Answer 28

spread out elements of an iterable object

console.log(…numbersArray) //1 2 3

Question 29

What is the value of rest?
const numbers = [13, 23, 43, 54, 15]
const [a, b, ...rest] = numbers

Answer 29

[43, 54, 15]