Arrays in javascript

 Store Multiple Values in one Variable using JavaScript Arrays:

With JavaScript array variables, we can store several pieces of data in one place.

You start an array declaration with an opening square bracket, end it with a closing square bracket, and put a comma between each entry, like this:

const sandwich = ["peanut butter", "jelly", "bread"];

You can store numbers in the arrays as well just don't use quotes around them.

Nest one Array within Another Array:

You can also nest arrays within other arrays, like below:

const teams = [["Bulls", 23], ["White Sox", 45]];

This is also called a multi-dimensional array.

Access Array Data with Indexes:

We can access the data inside arrays using indexes.

Array indexes are written in the same bracket notation that strings use, except that instead of specifying a character, they are specifying an entry in the array. Like strings, arrays use zero-based indexing, so the first element in an array has an index of 0.

Example

const array = [50, 60, 70];
array[0];
const data = array[1];

array[0] is now 50, and data is 60.

Note: There shouldn't be any spaces between the array name and the square brackets, like array [0]. Although JavaScript is able to process this correctly, this may confuse other programmers reading your code.

Modify Array Data With Indexes:

Unlike strings, the entries of arrays are mutable and can be changed freely, even if the array was declared with const.

Example:

const ourArray = [50, 40, 30];
ourArray[0] = 15;

Note: There shouldn't be any spaces between the array name and the square brackets, like array [0]. Although JavaScript is able to process this correctly, this may confuse other programmers reading your code.