Arrays in Javascript

What is an Array:

• An array is a collection of values stored in a single variable. Instead of creating multiple variables:

let a = 10;
let b = 20;
let c = 30;

we can use Array:

let numbers=[10,20,30];

Creating an array using literal:

Creating Empty Array:
let a=[];
console.log(a);

Initalize values:
let b=[10,20,30];
console.log(b);

O/P:
[]
10,20,30

Creating using new Keyword(constructor):

let a= new Array(10,20,30);
console.log(a)
O/P:
[10,20,30]

1. Accessing Elements of an Array:
Any element in the array can be accessed using the index number. The index in the arrays starts with 0.

let fruits = ["apple", "banana", "mango"];

Using index:
console.log(fruits[0]);
O/P:
apple

First element:
let a=fruits[0];
console.log(a);
O/P:
apple

Last element:
let last=fruits[fruits.length-1];
console.log(last);
O/P:
mango

2. Modifying Array elements:

let fruits = ["apple", "banana", "mango"];
fruits[1] = "orange";
console.log(fruits);
O/P:
["apple", "orange", "mango"]

3. Adding Elements to the Array:

• Elements can be added using push() and unshift() methods

push() → add at end
fruits.push("grape");
O/P:
"apple", "banana", "mango", "grape"

unshift() → add at beginning
fruits.unshift("kiwi");
"kiwi", "apple", "banana", "mango", "grape"

4. Removing Elements from an Array

• To remove the elements from an array we have different methods like pop(), shift(), or splice().

pop() → remove last
fruits.pop();

shift() → remove first
fruits.shift();

5. Array Length:

let fruits = ["apple", "banana", "mango"];
console.log(fruits.length);

O/P:
3

6. Increase and Decrease the Array Length:

let fruits = ["apple", "orange", "kiwi"]
console.log(fruits.length);
fruits.length=7;
console.log(fruits);
O/P:
3
7 ['apple', 'orange', 'kiwi', empty × 4]

7. Iterating Through Array Elements
We can iterate array and access array elements using for loop and forEach loop.

let fruits = ["apple", "orange", "kiwi"]
for(let i=0;i<fruits.length;i++){
    console.log(fruits[i])
O/P:
apple
orange
kiwi

8. Array Concatenation

let fruits = ["apple", "orange", "kiwi"]
let basket=[1,2];
console.log(fruits.concat(basket));

O/P:
['apple', 'orange', 'kiwi', 1, 2]

9. Conversion of an Array to String
We have a builtin method toString() to converts an array to a string.

let fruits = ["apple", "orange", "kiwi"]
console.log(fruits.toString());
O/P:
apple,orange,kiwi