JavaScript Arrays 101

Introduction

remember when we used to go to school , we had to take schoolbags for keeping books in one pocket, notebooks in one pocket, pencils in one pocket , water bottle in one pocket ,tiffin in one pocket ,,, similarly we programmers also need a system so that we can store multiple values together .. this concept is called Arrays

what are Arrays?

In JavaScript, an array is an ordered list of values. Each value, called an element, is assigned a number position in the array called its index.

The indexing starts at 0, so the first element is at position 0, the second at position 1, and so on.

Arrays can hold any type of data-such as numbers, strings, objects, or even other arrays

Create Arrays

you can create arrays using the [ ] brackets .

arrays can contain similar data types or different data types & even an array .

let numbers =[1,2,3,4,5];

let different=["text",12,true,[1,2,3]] 

Now when you want to access these element , you just have to - write the array name and with its index - like Arrayname[index] ,,,,,

ex- arr[0] -> indicates the first element

arr[1]-> indicates the second element

You can just update these also - like arr[0]="hello"

different[0]="sam"

Array length

Array length property tells how many elements are there in the array .

for example if i write - let L = different.length .,,,

and print L - it will show 4 , as in the above section it has 4 elements

How to Loop over an array :

Sometimes we want to print or process every element in an array.

We can do this using a loop.

Example using a for loop

let fruits = ["Apple", "Mango", "Banana", "Orange"];

for(let i = 0; i < fruits.length; i++){
  console.log(fruits[i]);
}

Output:

Apple
Mango
Banana
Orange

How it works

i = 0 → fruits[0] → Apple
i = 1 → fruits[1] → Mango
i = 2 → fruits[2] → Banana
i = 3 → fruits[3] → Orange

The loop continues until it reaches the array length.