Arrays in JavaScript behaves like an Object

In this article, we will learn how you check that javascript arrays behave like objects and why it happens. We will be showing the key and values in the array whether you define the key or not in an array of JavaScript.

Reason for Arrays behaving like an object:

• In JavaScript, there is no real Array instead of that it behaves in an array because the Array Class has been extended from the Object Class due to which properties of an object can be used in arrays as well.
• Every Class in JavaScript except primitive data type has been extended from the object class due to which properties of an object can be used in other data types as well.

Let's see the implementation for the above problem with an explanation as given below:

Example 1: If we will not be defining a key in the array then by default the key is set to the index of the value.

// Initialized the array
let arr = [];

// push() is used to add the element in last
arr.push(5);
arr.push(10);
arr.push("Prince");
arr.push("Aditya");

// Accessing the keys of array 
// using the object property
let keys = Object.keys(arr).join(" ");

// Accessing the values of array 
// using the object property
let values = Object.values(arr).join(" ");

console.log("The keys of array is: " + keys);
console.log("The values of array is: " + values);

Output:

The keys of array is: 0 1 2 3
The values of array is: 5 10 Prince Aditya

Example 2: In this, we will be defining the key manually and accessing the value as per the key by using the object property.

// Initialized the array
let arr = [];
arr["GeeksforGeeks"] = "GFG";
arr["Aditya"] = "Sharma";
arr["Prince"] = "kumar";

// Accessing the value from the array 
// using the object properties
let value1 = arr["GeeksforGeeks"];
let value2 = arr["Aditya"];
let value3 = arr["Prince"];
console.log("Accessing the value of GeeksforGeeks: " + value1);
console.log("Accessing the value of Aditya: " + value2);
console.log("Accessing the value of Prince: " + value3);

Output:

Accessing the value of GeeksforGeeks: GFG
Accessing the value of Aditya: Sharma
Accessing the value of Prince: kumar