Adding the key-value pairs to the Object in JavaScript

In this tutorial, we are going to learn about how to add a key/value pairs to an existing object in JavaScript.

Consider we have an object with two key-value pairs.

const user = {name: "gowtham", active: true}

To add a third key-value pair to an above object, we can do it in two different ways in JavaScript.

First way: Using dot notation

user.year = 2020;

In the above code, we have added third key-value pair to a user object by using the dot notation where year is key and 2020 is value.

Second way: Bracket notation

In the bracket notation, we need to pass key as a string like object['year'] instead of just the identifier name object[year].

user['year'] = 2020;

Note: The key is also called object property.