Building a Notion-like system with Socket.io And React 😍

What is this article about?

We are going to build a knowledge system like Click-Up and Notion. You will be able to add posts, write comments, tag other users and show it in their notifications.
In notion users can see what other users do in real-time without refreshing the page. This is why we will be using Socket.io. In the next article I will write about SSE (server sent events)

What is WebSocket?

WebSocket is a built-in Node.js module that enables us to create a real-time connection between a client and a server, allowing them to send data in both ways. However, WebSocket is low-level and doesn't provide the functionalities required to build complex real-time applications; this is why Socket.io exists.

Socket.io is a popular JavaScript library that allows us to create real-time, bi-directional communication between software applications and a Node.js server. It is optimised to process a large volume of data with minimal delay and provides better functionalities, such as fallback to HTTP long-polling or automatic reconnection.

Novu - the first open-source notification infrastructure

Just a quick background about us. Novu is the first open-source notification infrastructure. We basically help to manage all the product notifications. It can be In-App (the bell icon like you have in the Dev Community - Websockets), Emails, SMSs and so on.

I would be super grateful if you can help us out by starring the library 🤩
https://github.com/novuhq/novu

How to create a real-time connection with React & Socket.io

Here, we'll set up the project environment for the notion app. You'll also learn how to add Socket.io to a React and Node.js application and connect both development servers for real-time communication via Socket.io.

Create the project folder containing two sub-folders named client and server.



mkdir notion-platform
cd notion-platform
mkdir client server

Navigate into the client folder via your terminal and create a new React.js project.



cd client
npx create-react-app ./

Install Socket.io client API and React Router. React Router is a JavaScript library that enables us to navigate between pages in a React application.



npm install socket.io-client react-router-dom

Delete the redundant files such as the logo and the test files from the React app, and update the App.js file to display Hello World as below.



function App() {
    return (
        <div>
            <p>Hello World!</p>
        </div>
    );
}
export default App;

Add the Socket.io client API to the React app as below:



import { io } from "socket.io-client";

//👇🏻 http://localhost:4000 is where the server host URL.
const socket = io.connect("http://localhost:4000");

function App() {
    return (
        <div>
            <p>Hello World!</p>
        </div>
    );
}
export default App;

Navigate into the server folder and create a package.json file.



cd server & npm init -y

Install Express.js, CORS, Nodemon, and Socket.io Server API.



npm install express cors nodemon socket.io

Express.js is a fast, minimalist framework that provides several features for building web applications in Node.js. CORS is a Node.js package that allows communication between different domains.

Nodemon is a Node.js tool that automatically restarts the server after detecting file changes, and Socket.io allows us to configure a real-time connection on the server.

Create an index.js file - the entry point to the web server.



touch index.js

Set up a Node.js server using Express.js. The code snippet below returns a JSON object when you visit the http://localhost:4000/api in your browser.



//👇🏻index.js
const express = require("express");
const app = express();
const PORT = 4000;

app.use(express.urlencoded({ extended: true }));
app.use(express.json());

app.get("/api", (req, res) => {
    res.json({
        message: "Hello world",
    });
});

app.listen(PORT, () => {
    console.log(`Server listening on ${PORT}`);
});

Import the HTTP and the CORS library to allow data transfer between the client and the server domains.



const express = require("express");
const app = express();
const PORT = 4000;

//👇🏻 New imports
const http = require("http").Server(app);
const cors = require("cors");

app.use(express.urlencoded({ extended: true }));
app.use(express.json());
app.use(cors());

app.get("/api", (req, res) => {
    res.json({
        message: "Hello world",
    });
});

http.listen(PORT, () => {
    console.log(`Server listening on ${PORT}`);
});

Next, add Socket.io to the project to create a real-time connection. Before the app.get() block, copy the code below.



//👇🏻 New imports
.....
const socketIO = require('socket.io')(http, {
    cors: {
        origin: "http://localhost:3000"
    }
});

//👇🏻 Add this before the app.get() block
socketIO.on('connection', (socket) => {
    console.log(`⚡: ${socket.id} user just connected!`);

    socket.on('disconnect', () => {
      socket.disconnect()
      console.log('🔥: A user disconnected');
    });
});

From the code snippet above, the socket.io("connection") function establishes a connection with the React app, then creates a unique ID for each socket and logs the ID to the console whenever a user visits the web page.

When you refresh or close the web page, the socket fires the disconnect event showing that a user has disconnected from the socket.

Configure Nodemon by adding the start command to the list of scripts in the package.json file. The code snippet below starts the server using Nodemon.



//👇🏻 In server/package.json"
"scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "nodemon index.js"
}

You can now run the server with Nodemon by using the command below.



npm start

Building the user interface

Here, we'll create the user interface for the notion application to enable users to sign in, write posts, add comments, and tag other users.

Navigate into the client/src folder and create a components folder containing Login.js, Home.js, CreatePost.js, and NotionPost.js files.



cd client
mkdir components
cd components
touch Login.js Home.js CreatePost.js NotionPost.js

Update the App.js file to render the newly created components on different routes via React Router as below:



import { BrowserRouter, Routes, Route } from "react-router-dom";
import NotionPost from "./components/NotionPost";
import CreatePost from "./components/CreatePost";
import Home from "./components/Home";
import Login from "./components/Login";
import { io } from "socket.io-client";

const socket = io.connect("http://localhost:4000");

function App() {
    return (
        <BrowserRouter>
            <Routes>
                <Route path='/' element={<Login socket={socket} />} />
                <Route path='/dashboard' element={<Home socket={socket} />} />
                <Route path='/post/create' element={<CreatePost socket={socket} />} />
                <Route path='/post/:id' element={<NotionPost socket={socket} />} />
            </Routes>
        </BrowserRouter>
    );
}

export default App;

Navigate into the src/index.css file and copy the code below. It contains all the CSS required for styling this project.



@import url("https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@300;400;500;600;700&display=swap");
* {
    box-sizing: border-box;
    padding: 0;
    margin: 0;
    font-family: "Space Grotesk", sans-serif;
}
body {
    padding: 0;
}
.login {
    width: 100%;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}
.login > h2 {
    color: #00abb3;
    margin-bottom: 30px;
}
.loginForm {
    width: 70%;
    display: flex;
    flex-direction: column;
}
.loginForm > input {
    margin: 10px 0;
    padding: 10px 15px;
}
.home__navbar {
    width: 100%;
    height: 10vh;
    padding: 20px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    border-bottom: 1px solid #eaeaea;
}
.home__navbar > h2 {
    color: #00abb3;
}
.home__buttons {
    display: flex;
    align-items: center;
    justify-content: baseline;
}
.home__createBtn {
    padding: 10px;
    cursor: pointer;
    margin-right: 10px;
    background-color: #00abb3;
    border: none;
    outline: none;
    color: #fff;
}
.home__createBtn:hover,
.createForm__button:hover {
    background-color: #02595e;
}
.home__notifyBtn {
    padding: 10px;
    cursor: pointer;
    color: #00abb3;
    background-color: #fff;
    border: 1px solid #3c4048;
    outline: none;
    width: 100px;
}
.posts__container {
    width: 100%;
    min-height: 90vh;
    padding: 30px 20px;
}
.post {
    width: 100%;
    min-height: 8vh;
    background-color: #00abb3;
    border-radius: 5px;
    padding: 20px;
    display: flex;
    color: #eaeaea;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 15px;
}
.post__cta {
    padding: 10px;
    background-color: #fff;
    cursor: pointer;
    outline: none;
    border: none;
    border-radius: 2px;
}
.createPost {
    min-height: 100vh;
    width: 100%;
    padding: 30px 20px;
}
.createPost > h2 {
    text-align: center;
    color: #00abb3;
}
.createForm {
    width: 100%;
    min-height: 80vh;
    padding: 20px;
    display: flex;
    flex-direction: column;
}
.createForm__title {
    padding: 10px;
    height: 45px;
    margin-bottom: 10px;
    text-transform: capitalize;
    border: 1px solid #3c4048;
}
.createForm__content {
    padding: 15px;
    margin-bottom: 15px;
    border: 1px solid #3c4048;
}
.createForm__button {
    width: 200px;
    padding: 10px;
    height: 45px;
    background-color: #00abb3;
    color: #fff;
    outline: none;
    border: none;
    cursor: pointer;
    border-radius: 5px;
}
.notionPost {
    width: 100%;
    min-height: 100vh;
    background-color: #eaeaea;
    display: flex;
    flex-direction: column;
    padding: 30px 50px;
}
.notionPost__container {
    width: 90%;
    min-height: 70vh;
    margin-bottom: 30px;
}
.notionPost__author {
    color: #00abb3;
}
.notionPost__date {
    opacity: 0.4;
    font-size: 12px;
}
.notionPost__content {
    padding-top: 30px;
    line-height: 200%;
}
.comments__container {
    min-height: 70vh;
    border: 1px solid #3c4048;
    padding: 30px;
    box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.05), 2px 2px 3px 1px rgba(208, 213, 219, 0.28);
    border-radius: 3px;
}
.comments__inputContainer {
    display: flex;
    align-items: center;
    margin: 30px 0;
}
.comments__input {
    width: 50%;
    padding: 15px;
    margin-right: 15px;
}
.comments__cta,
.login__cta {
    padding: 15px;
    width: 200px;
    cursor: pointer;
    outline: none;
    border: none;
    background-color: #00abb3;
    color: #fff;
}
.comment {
    margin-bottom: 15px;
}

The Login page

Here, the application accepts the username and saves it in the local storage for user identification. Copy the code below into the Login component.



import React, { useState } from "react";
import { useNavigate } from "react-router-dom";

const Login = () => {
    const [username, setUsername] = useState("");
    const navigate = useNavigate();

    const handleLogin = (e) => {
        e.preventDefault();
        //The username 👉🏻 console.log({ username });
        localStorage.setItem("username", username);
        navigate("/dashboard");
    };
    return (
        <div className='login'>
            <h2>Sign in to HackNotion</h2>
            <form className='loginForm' onSubmit={handleLogin}>
                <label htmlFor='username'>Enter your username</label>
                <input
                    name='username'
                    id='username'
                    type='text'
                    value={username}
                    required
                    onChange={(e) => setUsername(e.target.value)}
                />
                <button className='login__cta'>LOG IN</button>
            </form>
        </div>
    );
};

export default Login;

The Home page

Copy the code below into the Home.js file. It represents the home layout for the application.



import React from "react";
import { useNavigate } from "react-router-dom";

const Home = () => {
    const navigate = useNavigate();

    const createPostBtn = () => navigate("/post/create");
    const readMoreBtn = () => navigate("/post/:id");

    return (
        <div className='home'>
            <nav className='home__navbar'>
                <h2>HackNotion</h2>
                <div className='home__buttons'>
                    <button className='home__createBtn' onClick={createPostBtn}>
                        CREATE POST
                    </button>
                    <button className='home__notifyBtn'>NOTIFY</button>
                </div>
            </nav>

            <div className='posts__container'>
                <div className='post'>
                    <h3>How to create a new Socket.io client</h3>
                    <button className='post__cta' onClick={readMoreBtn}>
                        READ MORE
                    </button>
                </div>

                <div className='post'>
                    <h3>Creating React Native project with Expo</h3>
                    <button className='post__cta' onClick={readMoreBtn}>
                        READ MORE
                    </button>
                </div>
            </div>
        </div>
    );
};

export default Home;

The NotionPost page

This page is dynamic and displays the content of each post via the ID passed into the URL. Here, users can read the notion post and add comments.

Copy the code below into the NotionPost.js file:



import React, { useState } from "react";

const NotionPost = () => {
    const [comment, setComment] = useState("");

    const handleAddComment = (e) => {
        e.preventDefault();
        console.log({ comment });
        setComment("");
    };

    return (
        <div className='notionPost'>
            <div className='notionPost__container'>
                <h1>How to create a new React Native project with Expo</h1>
                <div className='notionPost__meta'>
                    <p className='notionPost__author'>By Nevo David</p>
                    <p className='notionPost__date'>Created on 22nd September, 2022</p>
                </div>

                <div className='notionPost__content'>
                    For this article, I will use Puppeteer and ReactJS. Puppeteer is a
                    Node.js library that automates several browser actions such as form
                    submission.
                </div>
            </div>

            <div className='comments__container'>
                <h2>Add Comments</h2>
                <form className='comments__inputContainer' onSubmit={handleAddComment}>
                    <textarea
                        placeholder='Type in your comments...'
                        rows={5}
                        className='comments__input'
                        value={comment}
                        required
                        onChange={(e) => setComment(e.target.value)}
                    />
                    <button className='comments__cta'>Add Comment</button>
                </form>

                <div>
                    <p className='comment'>
                        <span style={{ fontWeight: "bold" }}>Scopsy Dima</span> - Nice post
                        fam!❤️
                    </p>
                </div>
            </div>
        </div>
    );
};

export default NotionPost;

The CreatePost page

Here, we'll create a simple layout that allows users to create posts by adding the title and its content. Users will also be able to tag other users using React Tag.

React Tag is a library that allows us to create tags easily via a single component. It provides several features, such as autocomplete based on a suggestion list, reordering using drag-and-drop, and many more.*

Copy the code below into the CreatePost.js file.



import React, { useState } from "react";
import { useNavigate } from "react-router-dom";

const CreatePost = () => {
    const navigate = useNavigate();

    const [postTitle, setPostTitle] = useState("");
    const [postContent, setPostContent] = useState("");

    //...gets the publish date for the post
    const currentDate = () => {
        const d = new Date();
        return `${d.getDate()}-${d.getMonth() + 1}-${d.getFullYear()}`;
    };

    //...logs the post details to the console
    const addPost = (e) => {
        e.preventDefault();
        console.log({
            postTitle,
            postContent,
            username: localStorage.getItem("username"),
            timestamp: currentDate(),
        });
        navigate("/dashboard");
    };

    return (
        <>
            <div className='createPost'>
                <h2>Create a new Post</h2>
                <form className='createForm' onSubmit={addPost}>
                    <label htmlFor='title'> Title</label>
                    <input
                        type='text'
                        required
                        value={postTitle}
                        onChange={(e) => setPostTitle(e.target.value)}
                        className='createForm__title'
                    />

                    <label htmlFor='title'> Content</label>
                    <textarea
                        required
                        rows={15}
                        value={postContent}
                        onChange={(e) => setPostContent(e.target.value)}
                        className='createForm__content'
                    />

                    <button className='createForm__button'>ADD POST</button>
                </form>
            </div>
        </>
    );
};

export default CreatePost;

Import React Tags into the CreatePost.js file:



import { WithContext as ReactTags } from "react-tag-input";

Update the CreatePost component to contain the code snippet below for creating tags with React Tags.



//👇🏻 The suggestion list for autocomplete
const suggestions = ["Tomer", "David", "Nevo"].map((name) => {
    return {
        id: name,
        text: name,
    };
});

const KeyCodes = {
    comma: 188,
    enter: 13,
};
//👇🏻 The comma and enter keys are used to separate each tags
const delimiters = [KeyCodes.comma, KeyCodes.enter];

//...The React component
const CreatePost = () => {
    //👇🏻 An array containing the tags
    const [tags, setTags] = useState([]);

    //...deleting tags
    const handleDelete = (i) => {
        setTags(tags.filter((tag, index) => index !== i));
    };

    //...adding new tags
    const handleAddition = (tag) => {
        setTags([...tags, tag]);
    };

    //...runs when you click on a tag
    const handleTagClick = (index) => {
        console.log("The tag at index " + index + " was clicked");
    };

    return (
        <div className='createPost'>
            <form>
                {/**...below the input fields---*/}
                <ReactTags
                    tags={tags}
                    suggestions={suggestions}
                    delimiters={delimiters}
                    handleDelete={handleDelete}
                    handleAddition={handleAddition}
                    handleTagClick={handleTagClick}
                    inputFieldPosition='bottom'
                    autocomplete
                />
                <button className='createForm__button'>ADD POST</button>
            </form>
        </div>
    );
};

export default CreatePost;

React Tags also allows us to customize its elements. Add the following code to the src/index.css file:



/*
You can learn how it's styled here: 
https://stackblitz.com/edit/react-tag-input-1nelrc
*/
.ReactTags__tags react-tags-wrapper,
.ReactTags__tagInput {
    width: 100%;
}
.ReactTags__selected span.ReactTags__tag {
    border: 1px solid #ddd;
    background: #00abb3;
    color: white;
    font-size: 12px;
    display: inline-block;
    padding: 5px;
    margin: 0 5px;
    border-radius: 2px;
    min-width: 100px;
}

.ReactTags__selected button.ReactTags__remove {
    color: #fff;
    margin-left: 15px;
    cursor: pointer;
    background-color: orangered;
    padding: 0 10px;
    border: none;
    outline: none;
}

.ReactTags__tagInput input.ReactTags__tagInputField,
.ReactTags__tagInput input.ReactTags__tagInputField:focus {
    margin: 10px 0;
    font-size: 12px;
    width: 100%;
    padding: 10px;
    height: 45px;
    text-transform: capitalize;
    border: 1px solid #3c4048;
}

.ReactTags__selected span.ReactTags__tag {
    border: 1px solid #ddd;
    background: #63bcfd;
    color: white;
    font-size: 12px;
    display: inline-block;
    padding: 5px;
    margin: 0 5px;
    border-radius: 2px;
}
.ReactTags__selected a.ReactTags__remove {
    color: #aaa;
    margin-left: 5px;
    cursor: pointer;
}

/* Styles for suggestions */
.ReactTags__suggestions {
    position: absolute;
}
.ReactTags__suggestions ul {
    list-style-type: none;
    box-shadow: 0.05em 0.01em 0.5em rgba(0, 0, 0, 0.2);
    background: white;
    width: 200px;
}
.ReactTags__suggestions li {
    border-bottom: 1px solid #ddd;
    padding: 5px 10px;
    margin: 0;
}
.ReactTags__suggestions li mark {
    text-decoration: underline;
    background: none;
    font-weight: 600;
}
.ReactTags__suggestions ul li.ReactTags__activeSuggestion {
    background: #fff;
    cursor: pointer;
}

.ReactTags__remove {
    border: none;
    cursor: pointer;
    background: none;
    color: white;
}

Congratulations! We've completed the layout for the notion application. Next, let's learn how to add all the needed functionalities with the Socket.io Node.js server.

Creating new posts with Socket.io

In this section, I'll guide you on how to create new posts and display them on the React app with Socket.io.

Update the addPost function within the CreatePost component by sending the newly created post to the server via Socket.io.



//👇🏻 Socket.io was passed from the App.js file
const CreatePost = ({ socket }) => {
    //...other functions

    const addPost = (e) => {
        e.preventDefault();

        //👇🏻 sends all the post details to the server
        socket.emit("createPost", {
            postTitle,
            postContent,
            username: localStorage.getItem("username"),
            timestamp: currentDate(),
            tags,
        });
        navigate("/dashboard");
    };

    return <div className='createPost'>...</div>;
};

Create a listener to the event on the server.



socketIO.on("connection", (socket) => {
    console.log(`⚡: ${socket.id} user just connected!`);

    socket.on("createPost", (data) => {
        /*👇🏻 data - contains all the post details 
             from the React app
        */
        console.log(data);
    });

    socket.on("disconnect", () => {
        socket.disconnect();
        console.log("🔥: A user disconnected");
    });
});

Create an array on the backend server that holds all the posts, and add the new post to the list.



//👇🏻 generates a random ID
const fetchID = () => Math.random().toString(36).substring(2, 10);

let notionPosts = [];

socket.on("createPost", (data) => {
    const { postTitle, postContent, username, timestamp, tags } = data;
    notionPosts.unshift({
        id: fetchID(),
        title: postTitle,
        author: username,
        createdAt: timestamp,
        content: postContent,
        comments: [],
    });
    //👉🏻 We'll use the tags later for sending notifications

    //👇🏻 The notionposts are sent back to the React app via another event
    socket.emit("updatePosts", notionPosts);
});

Add a listener to the notion posts on the React app via the useEffect hook by copying the code below:



//👇🏻 Within Home.js file

useEffect(() => {
    socket.on("updatePosts", (posts) => console.log(posts));
}, [socket]);

Displaying the posts

Save the posts into a state and render them as below:



import React, { useEffect, useState } from "react";
import { useNavigate } from "react-router-dom";

const Home = ({ socket }) => {
    const navigate = useNavigate();
    const [posts, setPosts] = useState([]);

    //👇🏻 Saves the posts into the "posts" state
    useEffect(() => {
        socket.on("updatePosts", (posts) => setPosts(posts));
    }, [socket]);

    const createPostBtn = () => navigate("/post/create");

    //👇🏻 Navigates to the NotionPost page to view
    //   all the post contents
    const readMoreBtn = (postID) => {
        navigate(`/post/${postID}`);
    };

    return (
        <div className='home'>
            <nav className='home__navbar'>
                <h2>HackNotion</h2>
                <div className='home__buttons'>
                    <button className='home__createBtn' onClick={createPostBtn}>
                        CREATE POST
                    </button>
                    <button className='home__notifyBtn'>NOTIFY</button>
                </div>
            </nav>

            <div className='posts__container'>
                {posts?.map((post) => (
                    <div className='post' key={post.id}>
                        <h3>{post.title}</h3>
                        <button className='post__cta' onClick={() => readMoreBtn(post.id)}>
                            READ MORE
                        </button>
                    </div>
                ))}
            </div>
        </div>
    );
};

export default Home;

So far, we can only view the posts when we add one. Next, let's make it possible for us to display the posts when we load the page.

Create a route on the server that returns the notion posts.



app.get("/api", (req, res) => {
    res.json(notionPosts);
});

Update the Home.js file fetch the notion posts and listen for new posts from the server.



useEffect(() => {
    function fetchPosts() {
        fetch("http://localhost:4000/api")
            .then((res) => res.json())
            .then((data) => setPosts(data))
            .catch((err) => console.error(err));
    }
    fetchPosts();
}, []);

useEffect(() => {
    socket.on("updatePosts", (posts) => setPosts(posts));
}, [socket]);

Completing the Notion Post component

In the previous section, you learnt how to create and display notion posts to users. Here, you'll learn how to show the contents of each notion post when you click the Read More button.

Update the readMoreBtn function within the Home.js file as below:



const readMoreBtn = (postID) => {
    socket.emit("findPost", postID);
//👇🏻 navigates to the Notionpost routenavigate(`/post/${postID}`);
};

The code snippet above gets the ID of the selected post and sends a Socket.io event containing the post ID to the server before redirecting to the post route.

Create a listener to the findPost event and return the post details via another Socket.io event.



socket.on("findPost", (postID) => {

  //👇🏻 Filter the notion post via the post ID
  let result = notionPosts.filter((post) => post.id === postID);

  //👇🏻 Returns a new event containing the post details
    socket.emit("postDetails", result[0]);
});

Listen to the postDetails event with the NotionPost component and render the post details as below:



import React, { useState, useEffect } from "react";
import { useParams } from "react-router-dom";

const NotionPost = ({ socket }) => {
    //👇🏻 gets the Post ID from its URL
    const { id } = useParams();

    const [comment, setComment] = useState("");
    const [post, setPost] = useState({});

    //👇🏻loading state for async request
    const [loading, setLoading] = useState(true);

    //👇🏻 Gets the post details from the server for display
    useEffect(() => {
        socket.on("postDetails", (data) => {
            setPost(data);
            setLoading(false);
        });
    }, [socket]);

    //👇🏻 Function for creating new comments
    const handleAddComment = (e) => {
        e.preventDefault();
        console.log("newComment", {
            comment,
            user: localStorage.getItem("username"),
            postID: id,
        });
        setComment("");
    };

    if (loading) {
        return <h2>Loading... Please wait</h2>;
    }

    return (
        <div className='notionPost'>
            <div className='notionPost__container'>
                <h1>{post.title}</h1>
                <div className='notionPost__meta'>
                    <p className='notionPost__author'>By {post.author}</p>
                    <p className='notionPost__date'>Created on {post.createdAt}</p>
                </div>

                <div className='notionPost__content'>{post.content}</div>
            </div>

            <div className='comments__container'>
                <h2>Add Comments</h2>
                <form className='comments__inputContainer' onSubmit={handleAddComment}>
                    <textarea
                        placeholder='Type in your comments...'
                        rows={5}
                        className='comments__input'
                        value={comment}
                        required
                        onChange={(e) => setComment(e.target.value)}
                    />
                    <button className='comments__cta'>Add Comment</button>
                </form>

                <div>
                    <p className='comment'>
                        <span style={{ fontWeight: "bold" }}>Scopsy Dima</span> - Nice post
                        fam!❤️
                    </p>
                </div>
            </div>
        </div>
    );
};

export default NotionPost;

The Comments section

Here, I'll guide you through adding comments to each notion post and displaying them in real-time.

Update the handleAddComment function within the NotionPost component to send the new comments details to the server.



const handleAddComment = (e) => {
    e.preventDefault();
    socket.emit("newComment", {
        comment,
        user: localStorage.getItem("username"),
        postID: id,
    });
    setComment("");
};

Create a listener to the event on the server that adds the comment to the list of comments.



socket.on("newComment", (data) => {
    const { postID, user, comment } = data;

//👇🏻 filters the notion post via its ID
let result = notionPosts.filter((post) => post.id === postID);

//👇🏻 Adds the comment to the comments list
    result[0].comments.unshift({
        id: fetchID(),
        user,
        message: comment,
    });
//👇🏻 sends the updated details to the React app
    socket.emit("postDetails", result[0]);
});

Update the NotionPost.js file to display any existing comments.



return (
    <div className='notionPost'>
        <div className='notionPost__container'>
            <h1>{post.title}</h1>
            <div className='notionPost__meta'>
                <p className='notionPost__author'>By {post.author}</p>
                <p className='notionPost__date'>Created on {post.createdAt}</p>
            </div>

            <div className='notionPost__content'>{post.content}</div>
        </div>

        <div className='comments__container'>
            <h2>Add Comments</h2>
            <form className='comments__inputContainer' onSubmit={handleAddComment}>
                <textarea
                    placeholder='Type in your comments...'
                    rows={5}
                    className='comments__input'
                    value={comment}
                    required
                    onChange={(e) => setComment(e.target.value)}
                />
                <button className='comments__cta'>Add Comment</button>
            </form>

            {/** Displays existing comments to the user */}
            <div>
                {post.comments.map((item) => (
                    <p className='comment' key={item.id}>
                        <span style={{ fontWeight: "bold", marginRight: "15px" }}>
                            {item.user}
                        </span>
                        {item.message}
                    </p>
                ))}
            </div>
        </div>
    </div>
);

Congratulations!🎊 You can now create posts and add comments with Socket.io. For the remaining part of this tutorial, I'll guide you through sending notifications to every user you tag in your post using Novu.

How to add Novu to a React and Node.js application

Novu allows you to add various notification types, such as email, SMS, and in-app notifications. In this tutorial, you will learn how to create a Novu project, add Novu to your React and Node.js projects, and send an in-app notification with Novu.

Install the Novu Node.js SDK on the server and the Notification Center in the React app.



👇🏻 Install on the client
npm install @novu/notification-center

👇🏻 Install on the server
npm install @novu/node

Create a Novu project by running the code below. A personalised dashboard is available to you.



👇🏻 Run on the client
npx novu init

You will need to sign in with Github before creating a Novu project. The code snippet below contains the steps you should follow after running npx novu init



Now let's setup your account and send your first notification
❓ What is your application name? Notionging-Platform
❓ Now lets setup your environment. How would you like to proceed?
   > Create a free cloud account (Recommended)
❓ Create your account with:
   > Sign-in with GitHub
❓ I accept the Terms and Condidtions (https://novu.co/terms) and have read the Privacy Policy (https://novu.co/privacy)
    > Yes
✔️ Create your account successfully.

We've created a demo web page for you to see novu notifications in action.
Visit: http://localhost:57807/demo to continue

Visit the demo web page http://localhost:57807/demo, copy your subscriber ID from the page, and click the Skip Tutorial button. We'll be using it later in this tutorial.

Congratulations!🎊 You’ve successfully added Novu to your React and Node.js project. Next, let’s learn how to add in-app notifications to the notionging application to notify users when we tag them to a post.

Adding in-app notifications with Novu

Create a Notify.js file within the src/components folder and copy the code below into the file. It contains the elements required for in-app notifications from the documentation.



import React from "react";
import {
    NovuProvider,
    PopoverNotificationCenter,
    NotificationBell,
} from "@novu/notification-center";
import { useNavigate } from "react-router-dom";

const Notify = () => {
    const navigate = useNavigate();

    const onNotificationClick = (notification) =>
        navigate(notification.cta.data.url);

    return (
        <div>
            <NovuProvider
                subscriberId='<YOUR_SUBSCRIBER_ID>'
                applicationIdentifier='<YOUR_APP_ID>'
            >
                <PopoverNotificationCenter
                    onNotificationClick={onNotificationClick}
                    colorScheme='light'
                >
                    {({ unseenCount }) => <NotificationBell unseenCount={unseenCount} />}
                </PopoverNotificationCenter>
            </NovuProvider>
        </div>
    );
};

export default Notify;

The code snippet above adds Novu notification bell icon to the Notify component, enabling us to view all the notifications within the application.

The NovuProvider component requires your Subscriber ID - copied earlier from http://localhost:57807/demo and your application ID available in the Settings section under API Keys on the Novu Manage Platform.

Import the Notify component into the Home.js file and display the bell icon as below:



return (
        <div className='home'>
            <nav className='home__navbar'>
                <h2>HackNotion</h2>
                <div className='home__buttons'>
                    <button className='home__createBtn' onClick={createPostBtn}>
                        CREATE POST
                    </button>
                    <Notify />
                </div>
            </nav>
    </div>
)

Next, create the workflow for the application, which describes the features you want to add to the application.

Select Notification from the Development sidebar and create a notification template. Click the newly created template, then, Workflow Editor, and ensure the workflow is as below:

From the image above, Novu triggers the Digest engine before sending the in-app notification.

Novu Digest allows us to control how we want to send notifications within the application. It collects multiple trigger events and sends them as a single message. The image above sends notifications every 2 minutes, and it can be effective when you have many users and frequent updates.

Click the In-Appstep from the image above and edit the notification template to contain the content below.



{{sender}} tagged  you to a post

Novu allows you to add dynamic content or data to the templates using the Handlebars templating engine. The data for the sender variable will be inserted into the template as a payload from the request within our app.

Save the template by clicking Update button and head back to your code editor.

Sending notifications with Novu

Since we want to send notifications to users when we tag them to a post, we will have to store each username on the server, show them on the suggestion list provided by React Tags, and send them notifications via Novu.

Update the handleLogin function within the Login.js file to send the username to the server when they sign in.



const handleLogin = (e) => {
    e.preventDefault();
    //👇🏻 sends the username to the server
    socket.emit("addUser", username);
    localStorage.setItem("username", username);
    navigate("/dashboard");
};

Listen to the event and store the username in an array on the server.



let allUsers = [];

socket.on("addUser", (user) => {
    allUsers.push(user);
});

Also, render the list of users via another route on the server.



app.get("/users", (req, res) => {
    res.json(allUsers);
});

To show the users within the React Tags suggestion list, you need to send a request to the API route, get the list of users, and pass them into the list.
Update the CreatePost function to fetch the list of users, and save them within the local storage before navigating the post/create route.



const createPostBtn = () => {
    fetchUser();
    navigate("/post/create");
};

const fetchUser = () => {
    fetch("http://localhost:4000/users")
        .then((res) => res.json())
        .then((data) => {
            //👇🏻 converts the array to a string
            const stringData = data.toString();
            //👇🏻 saved the data to local storage
            localStorage.setItem("users", stringData);
        })
        .catch((err) => console.error(err));
};

Next, retrieve all the users from the local storage and pass them into the suggestion list provided by React Tags for display within the CreatePost component.



const [users, setUsers] = useState([]);

useEffect(() => {
    function getUsers() {
        const storedUsers = localStorage.getItem("users").split(",");
        setUsers(storedUsers);
    }
    getUsers();
}, []);

const suggestions = users.map((name) => {
    return {
        id: name,
        text: name,
    };
});

To notify each tagged user, create a function that loops through the users on the server and sends them a notification via Novu to them.

Import and initiate Novu on the server.



const { Novu } = require("@novu/node");
const novu = new Novu("<YOUR_API_KEY>")

Update the createPost listener on the backend to send a notification to all tagged users.



//👇🏻 Loops through the tagged users and sends a notification to each one of them
const sendUsersNotification = (users, sender) => {
    users.forEach(function (user) {
        novuNotify(user, sender);
    });
};

//👇🏻 sends a notification via Novu
const novuNotify = async (user, sender) => {
    try {
        await novu
            .trigger("<TEMPLATE_ID>", {
                to: {
                    subscriberId: user.id,
                    firstName: user.text,
                },
                payload: {
                    sender: sender,
                },
            })
            .then((res) => console.log("Response >>", res));
    } catch (err) {
        console.error("Error >>>>", { err });
    }
};

socket.on("createPost", (data) => {
    const { postTitle, postContent, username, timestamp, tags } = data;
    notionPosts.unshift({
        id: fetchID(),
        title: postTitle,
        author: username,
        createdAt: timestamp,
        content: postContent,
        comments: [],
    });
    //👇🏻 Calls the function to send a notification to all tagged users
    sendUsersNotification(tags, username);

    socket.emit("updatePosts", notionPosts);
});

Congratulations! 💃🏻 We've completed the code for this project.

Conclusion

So far, you've learned how to set up Socket.io in a React and Node.js application, send messages between the client and a Node.js server, add Novu to a React and Node.js application, and send notifications with Novu.

This tutorial demonstrates what you can build using Socket.io and Novu. Feel free to improve on the project by adding an authentication library and saving the blog posts to a database that supports real-time communication.

The complete code for this tutorial is available here: https://github.com/novuhq/blog/tree/main/blogging-platform-with-react-socketIO
Thank you for reading!

P.S I would be super grateful if you can help us out by starring the library 🤩
https://github.com/novuhq/novu