Adding Array Elements

The simplest method to append a new element to an array is by employing the push() method.

Example

const fruits = [“Banana”, “Orange”, “Apple”];
fruits.push(“Lemon”); // Adds a new element (Lemon) to fruits

An alternative approach to adding a new element to an array involves utilizing the length property.

Example

const fruits = [“Banana”, “Orange”, “Apple”];
fruits[fruits.length] = “Lemon”; // Adds “Lemon” to fruits

Caution!

Adding elements with high indexes may result in creating undefined “holes” within an array.

Example

const fruits = [“Banana”, “Orange”, “Apple”];
fruits[6] = “Lemon”; // Creates undefined “holes” in fruits

Associative Arrays

Numerous programming languages accommodate arrays with named indexes, known as associative arrays or hashes.

Contrarily, JavaScript does not support arrays with named indexes; instead, arrays exclusively employ numbered indexes.

Example

const person = [];
person[0] = “John”;
person[1] = “Doe”;
person[2] = 46;
person.length; // Will return 3
person[0]; // Will return “John”

Caution!

When named indexes are utilized, JavaScript will reinterpret the array as an object. Consequently, certain array methods and properties may yield inaccurate outcomes.

Example

const person = [];
person[“firstName”] = “John”;
person[“lastName”] = “Doe”;
person[“age”] = 46;
person.length; // Will return 0
person[0]; // Will return undefined

The Difference Between Arrays and Objects

In JavaScript, arrays utilize numbered indexes, whereas objects employ named indexes.

Arrays are a distinct type of objects distinguished by their utilization of numbered indexes.

When to Use Arrays. When to use Objects.

JavaScript does not natively support associative arrays.
Objects are preferable when the element names are strings (text), while arrays are better suited for element names represented as numbers.