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Text lesson

JS Arrays

JavaScript Arrays

An array is a unique variable capable of containing multiple values simultaneously.

const cars = [“Saab”, “Volvo”, “BMW”];

Why Use Arrays?

If you possess a list of items (such as a list of car names), storing the cars in individual variables might appear like this:

let car1 = “Saab”;
let car2 = “Volvo”;
let car3 = “BMW”;

Yet, what if you aim to iterate through the cars to locate a particular one? Furthermore, what if your car count extends beyond just three to, say, 300?

The remedy lies in an array!

An array empowers you to store numerous values under a solitary name, and you can retrieve these values by referencing an index number.

Creating an Array

The simplest method to create a JavaScript Array is by using an array literal.

Syntax:

const array_name = [item1, item2, ...];

It’s customary to declare arrays using the const keyword.

Explore further about using const with arrays in the chapter titled “JS Array Const.”

Example

const cars = [“Saab”, “Volvo”, “BMW”];

Spaces and line breaks hold no significance. A declaration can extend across multiple lines.

Example

const cars = [
  “Saab”,
  “Volvo”,
  “BMW”
];

Another approach is to create an array and subsequently furnish its elements.

Example

const cars = [];
cars[0]= “Saab”;
cars[1]= “Volvo”;
cars[2]= “BMW”;

Using the JavaScript Keyword new

In the following example, an Array is created and values are assigned to it.

Example

const cars = new Array(“Saab”, “Volvo”, “BMW”);

Both examples above achieve the same outcome.

Using new Array() is unnecessary. For simplicity, readability, and faster execution, opt for the array literal method.

Accessing Array Elements

To access an element within an array, you refer to its index number.

const cars = [“Saab”, “Volvo”, “BMW”];
let car = cars[0];

Remember: Array indexes commence at 0.

[0] denotes the initial element. [1] signifies the subsequent element.

Changing an Array Element

This statement modifies the value of the initial element in the “cars” array.

cars[0] = “Opel”;

Example

const cars = [“Saab”, “Volvo”, “BMW”];
cars[0] = “Opel”;

Converting an Array to a String

The toString() method in JavaScript transforms an array into a string comprising its array values, separated by commas.

Example

const fruits = [“Banana”, “Orange”, “Apple”, “Mango”];
document.getElementById(“demo”).innerHTML = fruits.toString();

Result:

Banana,Orange,Apple,Mango