How to Build a Chat App With Next.js & Firebase

In this tutorial, we will guide you through building a simple chat application with Next.js and Firebase.

Njoku Samson Ebere • Mar 11, 2021

Next.js is a full stack framework built with JavaScript. In simpler terms, it's a combination of React library and Express Framework. If you are coming from a React background, then picking up Next.js will be relatively simple. In this tutorial, we'll show you how to build a simple chat application using Next.js and Firebase.

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How to install Next.js

Before proceeding with this, ensure you have Node.js 10.13 or later in stalled in your machine.

To install Next.js, run the following command in your terminal

Create a Next.js project

Let's create a Next.js boiler plate for the chatApp we are about to build. To do that, run the following command

Ensure you use the default settings when creating the project

Preview the project you just created

To get a preview of our project at the moment, we do the following:

Open the project in a terminal or just navigate into the project folder from the terminal

Start the server

This loads the project in your default browser like so:

img default page

Building out chat app

The chat application we are going to build will be made up of four features (sign in, sign out, view chat and send message).

This tutorial assumes you already have basic knowledge of Firebase, React and date-fns.

Now, let's get to work...

Installing dependencies

This project will be depending on date-fns for date/time manipulation/formatting and Firebase for back-end purpose. To install them, run the following command:

Initial setup

At this point, we want to get our project ready for what we are about to build. Do the following with me:

Open the project we just created in your choice editor and navigate to the pages/index.js file. Replace the code there with the following code

Import the following at the top of the file

Create a firebase project and get your configuration code, Initialize firebase below the imports like so

Do not forget to replace the configuration with your own configuration

Authenticating a user

We want to be able to automatically check if a user is logged in or not. To be able to do this, we will use the onAuthStateChanged method provided for us by firebase.

So we begin by creating an initial state for the user just above the return statement like so:

Next we auto-check the state of the user and update the state appropriately with the following code

But something has to trigger the user's state change. Yes! We need to sign in or sign out for that to happen. Let's create those!

Sign in

We will be using the signInWithPopup feature provided by firebase. So enter the following code above the return statement

Sign out

Since we are logging in a user, it will make sense if we allow them leave sometimes when they want. At least for security purpose you know. So let's sign out a user using the following code:

Rendering the authentication component

You will notice that so far, the functions we have been creating are useless because nothing triggers them. Now we want to trigger these functions depending on the user's authentication state. We will use 2 buttons (one for the sign in and the other for the sign out).

Enter the following code within the div tag

The code above displays the sign out button if a user is already signed in and it displays the sign in button if a user is signed out.

Check your browser for update. See mine below:


Viewing and sending chat messages

Now the moment we all have been waiting for is here. In this part, we will be able to send messages to our firestore database in firebase and view the messages in real time.

Let's begin by creating this component. Create a file and name it _Components/ChatRoom

Enter the following code in the file

Send messages

To send messages, we will add an empty section and a form in the return statement. The form will have an input box and a button like so

The empty section is used to automatically scroll down to the most recent message after a new message is sent

Next, let's get the database, user details, dummy space and set an initial state for newMessage above the return statement like so:

The db and user will be passed from the pages/index.js file

Still above the return statement, we will define a function that will be triggered anytime the form is submitted. Enter the following code

In the code above, anytime a message is sent, the text of the message, time/date and user details is collected and saved to a collection called messages. It then clears the input box and scrolls down the chat to the newest message

View chat messages

We want to view messages but not by continuously refreshing the page manually. We want it to happen without refreshing the page and we also want to see the message as soon as it is sent.

In order to achieve that, we will enter the following code above the return statement

The code above collects all the messages from the database, sort the messages by createdAt field and limits the messages to be displayed to 100

Now to render the messages, add the following code just above the dummy space in the return statement

In the code above, loops through all the messages collected and outputs each message and the user's details. One more thing, let's add our ChatRoom component to the pages/index.js file

Import the component like so:

import ChatRoom from "../Components/ChatRoom";

Add the component just below the nav tag like so:

Notice that it is at this point that we pass the user and db props down to the ChatRoom component

You can check your project in your browser now and try sending messages. See mine below


Looks cool! Yeah?

But it looks a bit unkempt. Let's add some CSS to our styles/global.css file to style the app

This is what my app looks like now


The source code of the simple chat application we just built can be found here.

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About the author

Njoku is a software engineer who is interested in building solutions to real world problems and teaching others about the things he knows. Something he really enjoys doing aside writing codes and technical articles is body building.

Njoku Samson Ebere


He is a software engineer who is interested in building solutions to real world problems and teaching others about the things he knows. Something he really enjoys doing aside writing codes and technical articles is body building.

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