Build a simple chat app with node.js and

To develop a real chat application, we have to put in place a real-time system of sending/receiving data. It will be impossible to do it with a relational database and Ajax calls. Thank’s to WebSocket and the library, it becomes easy.

You can follow this tutorial with my repo Github:

Technical stack

Here is the technical stack that you are using for this app :

WebSockets and

WebSockets is a protocol that allows a bilateral synchronous exchange between a client and a server.

In the classic web, a client requests to a server and a server responds sending it back the data. This system is impossible for a chat app.

In WebSockets, the server can send data to the client, but the client can too ! A WebSocket is a kind of communication pipe opened in two directions. is a library based on this protocol to make the use of WebSockets easier.

The Javascript mafia

Node.js is a Javascript back-end technology executed by the server as PHP, Ruby or Python. JavaScript uses events. Node.js keeps this particularity so it is easy to make asynchronous code.

Node.js comes with its own package manager: npm. It becomes easy to install, update, delete packages.

In this tutorial, we are going to use express.js. It’s a micro web framework based on node.js.

Set up of the development environnement

First of all, we need to configure our development environment.

The first thing to do is to start npm, our packages manager. To do so, open a new terminal, create a new repository which will contain our project, go in it and initialize npm:

$ mkdir createSimpleApp
$ cd createSimpleApp
$ npm init

npm will ask you for several information. If you want to skip that, press enter until the end. Now if you look at your project, we will find a new file : package.json. This file is listing all your dependencies.

So now, we are ready to install the packages needed to develop our chat app! We are going to need these packages:

  • express: the micro web application framework for node.js
  • Nodemon: a package that will detect any changes and restart our server. We will use it instead of the classic node command.
  • ejs: a template engine to simplify the production of HTML
  • the famous package than manage WebSockets

To install them on our environment, it is super easy:

$ npm install --save package_name

I let you do the work for our 4 packages.

In your package.json, you could add this line into your scripts key:

“start”: “nodemon app”

With this line, you will be able to launch your app only with one commande using nodemon:

$ npm run start

Our environment is set up, we are ready to develop our application.

The chat app

Architecture of the app

First of all, we have to separate to part in the development of an application: the client part and the server part. We will have to develop the two parts to make our application up and running.

The server will be handled by node.js to make all the engineering (launch the packages and the website). This code will not be seen by the client.

The client part will be loaded on the computer of the client. He will have direct access to the files (html/css and js).

Server side:

We have to create the file app.js that will launch our server and all the packages.

This bunch of code is actually initializing our express app. If you go to http://localhost:3000, you will see a gentle message.

Now we just need to configure to be ready to deep dive into the WebSocket world.

Here, the io object will give us access to the library. io object is now listening to each connection to our app. Each time a new user is connecting, it will print out “New user connected” in our console.

If you try to reload our browser on localhost, nothing happened… Why ? Because our client side is not yet ready.

For the moment is only installed on the server part. Next, we will do the same work on the client side.

Client side

We just have to change a line in our app.js. In fact, we don’t want to display a « Hello world » message, but a really window with a chat box, inputs to write username/message and a send button. To do that we have to render an html file (which will be in our case an ejs file) when accessing the “/” root.

So you need to apply the render method to the res object.

In the other side, you will have to create a views folder, with an index.ejs file in it. The css will be in a public folder:

Our localhost:3000 will look like this :

So now that we have our basic template, we have to « install » on each client which will attempt to connect to our server. To do that, we have to import the library on the client side:

<script src=”"></script>

The only way to work with is in a .js file. So at the end of your body add these lines:

<script src=”"></script>
<script src=”chat.js”></script>

And create a chat.js file in the public folder.

For the moment, just write this in it :

As you probably guessed, when the client will load this file, it will automatically connect and so create a new socket.

So when you refresh the page, we will see « New user connected » in your terminal.

Send and receive data


When a user connects to our application, we will set him/her a default username, for example “anonymous”. To do that we have to go on the server side (app.js) and add a key to the socket. Actually, socket represent each client connected to our server.

We also will listen to any call made in « change_username ». If a message is sent to this event, the username will be changed.

On the client side, the goal is to do the opposite. Each time the button change username is clicked, the client will send an event with the new value.


For the messages, it is the same principle!



For the new_message event, you can see that we call the sockets property of io. It represents all the sockets connected. So this line will actually send a message to all the sockets. We want that to show a message sent by a user to all (and itself included).

Here is the final result of our chat app:

Little improvement

We can add a quick improvement to make our application more realistic. We will add the « XXX is typing… » message.

To do so, it is very easy.

After adding an HTML element in our index.ejs, we just add a jQuery event listener on typing and send a socket event named typing.

On the other side, we listen to typing and we broadcast a message. Broadcasting means sending a message to everyone else except for the socket that starts it.


See, this application is really easy to code. Before knowing the existence of WebSockets and, I thought this kind of application was really hard to code !

To improve this app, here is a list of functionalities to add:

  • A registration system with the possibility to chat in a one-to-one chatroom
  • History of all the conversations
  • Online/offline labels
  • Copy every features of WhatsApp !

Noufel Gouirhate

Producers and Writers on Cassper’s ‘Thuto’ album

Cassper Nyovest’s Thuto album was released in 2017 and  below are all the Producers and Writers:

1. Confused (feat. Goapele)

Produced by: Alie Keys
Written by: Cassper Nyovest, Goapele

2. I Wasn’t Ready For You

Produced by: Alie Keys
Written by: Cassper Nyovest, Tshego

3. As Karma Would Have It

Produced by: Alie Keys
Written by: Cassper Nyovest

4. Destiny (feat. Goapele)

Produced by: ANATII, Alie Keys, Cassper Nyovest
Written by: Cassper Nyovest, Guffy, Jabulani Ndaba (Malaika), Tshidi Mholo (Malaika), Bongani Nchang (Malaika)

5. Superman (feat. Tsepo Tshola)

Produced by: Alie Keys, Cassper Nyovest
Written by: Cassper Nyovest, Tsepo Tshola

6. Bentley Coupe

Produced by: Alie Keys, Cassper Nyovest
Written by: Cassper Nyovest

7. Nyuku

Produced by: Gobbla
Written by: Cassper Nyovest

8. We Living Good (feat. Tshego)

Produced by: Alie Keys, Cassper Nyovest
Written by: Cassper Nyovest, Tshego

9. Top Floor (LifeWasNeverTheSame)

Produced by: Alie Keys, Cassper Nyovest
Written by: Cassper Nyovest, DIDI Monsta

10. Top Shayela (feat. Nadia Nakai)

Produced by: Gobbla
Written by: Cassper Nyovest, Nadia Nakai (kandava)

11. Tito Mboweni

Produced by: Gemini Major
Written by: Cassper Nyovest

12. Touch The Sky

Produced by: Alie Keys
Written by: Dennis Ferrer, MIA Tittavilla, Cassper Nyovest

13. Ng’yekeleni (feat. Black Thought)

Produced by: Lae, Fenesse, Zero
Written by: Cassper Nyovest, Black Thought

14. Push Through The Pain

Produced by: Alie Keys
Written by: Cassper Nyovest

15. Baby Girl

Produced by: Dj Abza
Written by: Cassper Nyovest, Bunny Sigler, Kenneth Gamble, Cornell Haynes, Antoine Macon

16. Amen Hallelujah

Produced by: Gobbla
Written by: Cassper Nyovest

Introduction to Validation in React with Yup

The JavaScript Object Schema Validator and Object Parser to use with React

In this article we will visit why you should be using Yup in your React projects, what it does exactly, and how to make the most out of the package to simplify your code, with examples.

Yup is designed for front-end browser based use. If you are interested in server-side object schema validation with NodeJS, take a look at my article on Joi:

Why should you care about Yup?

Yup makes our lives far easier for validating the data our apps consume and manipulate, in an abstract way that does not interfere with the rest of our business logic.

Web apps built on JavaScript Frameworks are now highly interactive and mutable in and of themselves; that is what the end user has come to expect. With this comes a large amount of data exchange, whether it be from API requests, form submissions, or custom objects to handle our state.

We need to make sure we are delivering data that our components expect to work with, otherwise we will be dealing with unintended consequences in the form of failed component renders or app crashes — we don’t want this.

The general gist of Yup

So how does Yup work exactly?

With Yup, we create a Yup formatted object that resembles our intended schema for an object, and then use Yup utility functions to check if our data objects match this schema — hence validating them.

A Schema Object

Let’s use form validation as a use case for our Yup example.

Note: Form validation is by no means the only use case for Yup — use it to validate any object that you need to, whether you are retrieving data from your APIs or an external API library, or simply working with multiple objects or arrays within your project that need to adhere to a particular schema.

With that said, now imagine I am creating a checkout address form — which may resemble the following structure:

    email_address: email <required>
    full_name: string, <required>
    house_no: int,
    address_1: string <required>,
    address_2: string,
    post_code: string <required>
    timestamp: date <required>

This is the type of data I am expecting from this form, or my schema for a particular object. If my object does not match this schema, it is not valid.

Notice that I have treated the email_address field as an email data type. This is not an error. Yup can test whether a value is an email address with one method call . Likewise with our timestamp value — Yup can test whether this value is a date.

What does this look like as a Yup schema object? Something like this:

const checkoutAddressSchema = yup.object().shape({
  email_address: yup
  full_name: yup
  house_no: yup
  address_1: yup
  address_2: yup
  post_code: yup
  timestamp: yup
      .default(() => (new Date()),

A Yup schema is an immutable object responsible for validating an object.

This code is self explanatory: We can see for ourselves the responsibility of this object in a detailed way without having to add a single comment.

Each validator has its own method. This granularity allows us as developers to combine as many validators as we see fit for our data validation.

Data types such as stringintegerbooleanarrayobject and date are all callable validators within Yup, making it simple for Yup newcomers to begin using the code.

However, Yup goes way beyond simple data types. In the above example we also use validators like emailrequired, and positive, allowing me to check whether a value is representative of an email address, whether a value exists and whether a number is positive respectively. (we also have notRequired to use for greater readability of your schema).

This is great, abstract, reusable design. We can even assign default values with an embedded function, as the above example demonstrates with the timestamp field:

   timestamp: yup
      .default(() => (new Date()),

default() can be anything you wish to assign: it takes any value. The function can be expanded and treated like any other to include any logic you need to process in order to generate a default value:

   timestamp: yup
      .default(() => {
         //check for stuff           
         return new Date();

Validating Objects with My Schema

Now we have a schema for our checkout address form, we can then use it to validate the data we receive from it. Let’s say I receive the following data:

let addressFormData = {
   email_address: '',
   full_name: 'Ross Bulat',
   house_no: null,
   address_1: 'My Street Name',
   post_code: 'AB01 0AB',

As you can see, the address_2 and timestamp fields are missing from here — but they are not required in our schema, so the object will still be valid.

From here I would like to demonstrate 3 things:

  • Check if my object is valid. So a true or false result of whether my object is indeed a valid checkout address object.
  • Validate the object. E.g. use my schema to fill in any default values. This also type casts our object.
  • Visit the cast() method of Yup, that type casts an object without validating it.

Checking if the object is valid

To do this, we use yup.isValid(), which will look like the following when applied to our example:

const valid = await checkoutAddressSchema.isValid(addressFormData);

isValid() returns a promise, so we can either treat this with async and await as demonstrated above, or use callback syntax:

  .then(function(valid) {
     //valid - true or false

I prefer using await for cleaner syntax.

Validating the Object

In most cases we will require actually validating the object: process it to adhere to your schema expectations. In our example, we are expecting a timestamp value, and we have a default value if it is missing.

Let’s validate our address form with the following:

await checkoutAddressSchema.validate(addressFormData);

Now our object will be suitable for further processing.

Casting an Object

With the above example, validate(), we are checking whether our data is valid, and we are running validation on it. This is a handy shortcut that you may find you use the majority of time. However, we could just run an object through a cast() method that checks and fixes its types.

With our checkout address form, we may have a string that represents our house_no, whereas my schema expects an integer. cast() will fix this. It would also convert a timestamp string into our Date object if we indeed provided a timestamp string.

Cast is called like so:


Indispensable Tool?

At this point it is becoming clear that Yup adds an extra vital layer of data security to our apps in a concise way. Validation becomes much less of a headache, and actually a joy to write and read because of the simplicity of the syntax and abstraction of the Yup library.

To expand your initial understanding of Yup, let’s visit some other useful methods available within the package.

Miscellaneous Useful Methods

  • Remember our form data structure outlined at the top of the article? This can be retrieved from a Yup object with the describe() methoddescribe() collects the object schema details and serializes them into a separate object.
  • Want to combine 2 schemas into one? Use the concat() method. Perhaps you are combining multiple objects into one API call body, and therefore want to validate the entire body with one Yup object. concat() will come in handy for this.
  • Aborting validation early. By default Yup runs through an entire validation process and collects errors as it runs, and returns them all once validation is complete. We may not want to do this. We can use abortEarly to stop validation execution as soon as the first error crops up. abortEarly is passed as an options argument within validate():
await checkoutAddressSchema.validate(addressFormData, { abortEarly: false })
  • Yup has some great string utilities, such as trim(), that removes whitespace around a string. uppercase() and lowercase() are available to enforce capitalising or not.
  • Yup also has some great number utilities, such as min() and max(), as well as round()morethan()lessthan(), and truncate().
  • Yup supports regex, allowing you to utilise regular expressions.

Installing Yup in React Projects

Let’s move on how to install Yup in your projects, and visit some resources available for further reading.

Visit the NPMJS page or Github project for their official documentation.

Install yup with npm using the following command:

npm i yup

Importing Yup

Yup has the flexibility to be imported as an entire library, or as separate components that only your component needs.

Import the entire library with:

import * as yup from 'yup';

I recommend importing the entire library as you start developing, saving you the hassle of revisiting your imports every time you introduce a new Yup object as your forms evolve. When your app is ready to be built, revisit Yup to check whether you are only using a limited amount of components — perhaps you are only utilising the required and string objects — in this case we can simply import those 2 things:

import { string, required } from 'yup';

Overall though, if you are utilizing more than around 5 components, it can become a code smell to be importing this many objects.

Where to go from here

Now you should have a solid understanding of what Yup is, why it is used, and perhaps some ideas on how it can be implemented in your projects!

Take some time to explore the documentation, which lists all the validators available. Only after exploring everything the package has to offer will you have a well-rounded understanding of how it can fully benefit your apps.

However, Yup can easily be built upon by simply refactoring your validators, so there is no harm in jumping straight into some implementation to increase familiarity of the workflow, before jumping into more documentation detail.

Yup may continue to play a greater role within your app as development progresses, therefore you may also find yourself refactoring some data structures to further take advantage of the Yup workflow in the form of abstracting your data into smaller, more reusable formats.

Ross Bulat

Most popular Medium publications welcoming submissions

Here’s a good Medium leaderboard if you’re looking for an easy way to find even more publications.

Most popular websites looking for content

Here are places where you can promote your content. These can be considered as low hanging fruit and are a great place to start in your outreach efforts.