Lesson 8: Arrays and Applications

Question 1

What does an Array do?

Answer 1

Stores an ordered list of values under a single name.

Question 2

Show an example of an empty Array:

Answer 2

let myArray = [ ];

Question 3

What is an Array Property do?

Answer 3

Returns the number of elements in the array.

Question 4

Show how to delete a value from an Array:

Answer 4

delete myArray[2];

Question 5

concat:

Answer 5

Merges elements in multiple arrays and returns the merged result.

Question 6

toString:

Answer 6

Returns the string of all items in the array.

Question 7

indexOf:

Answer 7

Returns the index of the first matching item in the array.

Question 8

lastIndexOf:

Answer 8

Returns the index of the last matching item in the array.

Question 9

push:

Answer 9

Adds a new value to the end of the array.

Question 10

pop:

Answer 10

Removes the last item from an array.

Question 11

Shift:

Answer 11

Removes the first item in the array.

Question 12

Unshift:

Answer 12

Inserts a new item to the beginning of the array.

Question 13

What does sort() do?

Answer 13

Sorts an arrays elements alphabetically.

Question 14

What does reverse() do?

Answer 14

Reserves elements sequence in the array.

Question 15

What does the forEach method do?

Answer 15

Accepts a function name as an argument.

Question 16

What is the function parameter also called?

Answer 16

A callback function.

Question 17

What is the map() method used for?

Answer 17

Returning a new array that replaces each value with the return value of the callback function.

Question 18

What does the Three Dot (…) notation do?

Answer 18

It will spread out the elements of that array.

Question 19

Show an example using the Dot Notation:

Answer 19

const numArr1 = [20, 30];
const numArr2 = [50, 60];
let numArr3 = [1, ...numArr1, ...numArr2, 80];

Question 20

What is Initializing an Array?

Answer 20

Entering preloaded data at the time the array is created.

Question 21

Show an example of an initialized array:

Answer 21

var myArray = [‘Monday’, ‘Tuesday’];

Question 22

join():

Answer 22

Joins all of an arrays elements into a single string.

Question 23

What is ‘for-of’ used for?

Answer 23

Looping through interable structures