Array

Question 1

Arrays are what types of data ?

Answer 1

they are of type ‘object’ and data type in javascript.

Question 2

How many types of arrays do we have

Answer 2

2 types
arrays literals and constructor array

Question 3

how do we set arrays

Answer 3

it has to be in a variable and has value s
const number = [12, “hello”, true, false];
[ elements in the square brackets]

Question 4

How do access values in an array?

Answer 4

Array are number based this means they start from number 0
const numbers = [12,13,14, 2,15,24,188]
let x;
x = numbers[2]
console.log(x)
we can also use template literals
my favourite number is ${numbers[3]};

Question 5

Methods in arrays
what does method push do ?

Answer 5

it adds a value at the end of an existing array
arr.push(100);

Question 6

what does pop do

Answer 6

it removes a value from the array at the end.
arr.pop();

Question 7

what does unshift do?

Answer 7

it adds a value at the beginning of the array
arr.unshift(99);

Question 8

what does shift do?

Answer 8

it removes a value from the beginning of the array
arr.shift()

Question 9

what does reverse do

Answer 9

it reverses the values from beginning to the end
arr.reverse();

Question 10

what does includes method do ?

Answer 10

this method checks if the array list includes a specific value in the array and return a boolean value true or false, if the value is there its going to return true if not
it will return false.
arr.includes(200);

Question 11

what does indexOf do?

Answer 11

it gives you or return the index of a value

Question 12

what does slice do?

Answer 12

it will slice the array and return the array in range of the slice
arr.slice(1, 4) “it will return within that range”
and we have the start index to the index you want returned.

Question 13

what does splice do ?

Answer 13

it works like slice but it manipulate/change the original array. the first is the start index the second is the elements you want to go over
arr.splice(1, 4);

Question 14

how do we chain methods ?

Answer 14

x = arr.splice(1, 4).reverse()toString();

Question 15

What is nesting in Array ?

Answer 15

Is having an array as an Index inside of another array

Question 16

examples

Answer 16

const fruits = [‘apple’, ‘banana’, ‘orange’];

const berries = [‘strawberries’, ‘blueberry’, ‘raspberry’];
fruits.push(berries);

console.log(fruits)

Question 17

how do we access in a nested array ?

Answer 17

let x;

x = fruits[1][1];
console. log(x);

Question 18

How do we concatenate arrays

Answer 18

It’s not putting the array inside the array, but it’s taking the items from one array and basically adding them into a different array

x = fruits.concat(berries);

Question 19

what is spread operator

Answer 19

spread operator(. . .);
the spread operator, is represented by three dots and this can be used in arrays and objects

x = [. . .fruits, . . .berries];
console.log(x)
NB
‘does the same operations as concat
in an event that you want to take something from 1 and 1 array and spreed those items across inside another array
‘

Question 20

how to flatten an array when this is when you have arrays nested in an array

Answer 20

const arr = [1, 2, 3, [4, 5], 6, [7, 8];

x = arr.flat();

Question 21

Static array object

Answer 21

one of its use is to check if something is an array

Array.isArray(fruits)

Question 22

static object from

Answer 22

This method will create an Array from an array like value.
this is very useful when it comes to HTML collection or node list
x = Array.from (12345)
it will convert string into an Array