JavaScript Objects

JavaScript object is a variable that can store multiple data in key-value pairs.

Here's a quick example of the JavaScript object. Read the rest of the tutorial for more.


// student object const student = { firstName: "Jack", rollNo: 32 };
console.log(student); // Output: { firstName: 'Jack', rollNo: 32 }

Here, student is an object that stores the first name and the roll number of students as key-value pairs.

Create JavaScript Objects

The syntax of JavaScript object is:

const objectName = {
    key1: value1,
    key2: value2,
    keyN: valueN


  • objectName - Name of the object.
  • key1: value1 - The first key-value pair.
  • key2: value2 - The second key-value pair.
  • keyN: valueN - The Nth key-value pair.

Each key-value pair has a colon : between them and is separated by a comma ,.

Example 1: JavaScript Objects

// create person object const person = { name: "John", age: 20 };
console.log(person); // Output: { name: "John", age: 20 }

In the above example, name: "John" and age: 30 are key-value pairs.

Note: You can also create objects in a single line. For example,

const person = { name: "John", age: 20 };

However, it's preferable to break down objects into multiple lines for better readability.

JavaScript Object Properties

In JavaScript, the key-value pairs of an object are referred to as properties. For example,

const person = {
    name: "John",
    age: 20,

Here, name: "John" and age: 30 are the properties of the object person.

Key-Value Pairs are Object Properties in JavaScript
JavaScript Object Properties

Access Object Properties

You can access the value of a property by using its key.

1. Using Dot Notation

const dog = {
    name: "Rocky",

// access property console.log(;
// Output: Rocky

2. Using Bracket Notation

const cat = {
    name: "Luna",

// access property console.log(cat["name"]);
// Output: Luna

JavaScript Object Operations

In JavaScript, we can perform various operations on object properties like modifying, adding, deleting, and so on. Let's discuss some of them.

1. Modify Object Properties

We can modify object properties by assigning a new value to an existing key. For example,

const person = {
    name: "Bobby",
    hobby: "Dancing",

// modify property person.hobby = "Singing";
// display the object console.log(person); // Output: { name: 'Bobby', hobby: 'Singing' }

In the above example, we used the dot notation to change the value of the hobby key from Dancing to Singing.

2. Add Object Properties

const student = {
    name: "John",
    age: 20,

// add properties student.rollNo = 14; student.faculty = "Science";
// display the object console.log(student); // Output: { name: 'John', age: 20, rollNo: 14, faculty: 'Science' }

In the above example, the keys rollNo and faculty do not exist within the object. Hence, when we assign values to these keys, new properties are added to the object.

3. Delete Object Properties

We can remove properties from an object using the delete operator. For example,

const employee = {
    name: "Tony",
    position: "Officer",
    salary: 30000,

// delete object property delete employee.salary
// display the object console.log(employee); // Output: { name: 'Tony', position: 'Officer' }

JavaScript Object Methods

We can also include functions inside an object. For example,

const person = {
    name: "Bob",
    age: 30,

// use function as value greet: function () { console.log("Bob says Hi!"); }
// call object method person.greet(); // Bob says Hi!

Here, we have assigned a function as a value for the greet key.

These functions that are defined inside objects are called methods.

Note: Just like we use () to call a function, we must use () to call methods.

You will learn more about JavaScript Methods in the next tutorial.

JavaScript Nested Objects

What is a nested object?

A nested object contains another object as a property. For example,

// outer object student
const student = {
    name: "John",
    age: 20,

// contains another object marks marks: { science: 70, math: 75 }
}; // display student console.log(student); // Output: { name: 'John', age: 20, marks: { science: 70, math: 75 } }

In the above example, the student object contains another object nested inside it called marks.

Access Properties of Nested Objects

We can access a nested object's property using both the dot and bracket notations.

const student = {
    name: "John",
    age: 20,

    marks: {
        science: 70,
        math: 75

// use dot notation console.log(; // 70 // use bracket notation console.log(student["marks"]["math"]); // 75

Also Read:

Video: JavaScript Objects

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