Understanding Arrays in JavaScript

Introduction

An array in JavaScript is a type of global object that is used to store data. Arrays consist of an ordered collection or list containing zero or more data types, and use numbered indices starting from 0 to access specific items.

Arrays are very useful as they store multiple values in a single variable, which can condense and organize our code, making it more readable and maintainable. Arrays can contain any data type, including numbers, strings, and objects.

To demonstrate how arrays can be useful, consider assigning the five oceans of the world to their own variables.

// Assign the five oceans to five variables
const ocean1 = "Pacific";
const ocean2 = "Atlantic";
const ocean3 = "Indian";
const ocean4 = "Arctic";
const ocean5 = "Antarctic";

This method is very verbose, and can quickly become difficult to maintain and keep track of.

Using arrays, we can simplify our data.

// Assign the five oceans
let oceans = [
	"Pacific",
	"Atlantic",
	"Indian",
	"Arctic",
	"Antarctic",
];

Instead of creating five separate variables, we now have one variable that contains all five elements. We used square brackets — [] — to create an array.

To access a specific item, append its index to the variable.

// Print out the first item of the oceans array
oceans[0];

Output
Pacific

In this tutorial, we will learn how to create arrays; how they are indexed; how to add, modify, remove, or access items in an array; and how to loop through arrays.