Starting with Express.js: Building a Simple Server Tutorial

Nowadays, one of the most pivotal frameworks in the web development landscape, according to Stack Overflow statistics, is Express. Powering a significant portion of Node.js applications, Express has become the go-to framework for developers seeking efficiency and flexibility in building web servers and APIs. Its simplicity, robust features and vibrant ecosystem make Express.js an indispensable tool, enabling developers to create scalable and maintainable applications with ease. In this post, we'll delve into the fundamentals of Express, exploring why it has earned its popularity and guiding you through the process of building your first simple server. Let's get started.

Install Express Framework

First of all, we need to install Node.js from the official website and create a folder for our app "simple_web_server" for example.

Next, open a terminal in the folder we created, and we will use the terminal in Visual Studio Code. And use the "npm init" command to generate a package.json file.

Great, now we have a package.json file in our folder, it must be the easiest way of starting a new project, because in this case "node package manager" will help us with all dependencies.

To install Express just use another command: "npm install express", and that's it all dependencies needed to work with Express will be settled automatically.

Also, we will work with "npm" so let's configure our environment so that we do not always call the "node ..." command to start a project. Open the package.json file and inside "scripts" add the new command "start" that will launch our "expressWebServer.js" file. In my case "scripts" will look like this:

"scripts": {
  "test": "echo \"Error: no test specified\" && exit 1",
  "start": "node expressWebServer.js"
},

Now to start our express web server we need to use the "npm start" command. But our server file is still empty, so let's move to the next step.

Create a Simple Express Server

Let's open our "expressWebServer.js" file and start working. In the beginning, we need to import the express module into our file with the "require()" function and create an instance of Express.

Then we can define our first express route by using the "GET" method ( in Express "GET" method used to define a route for handling GET requests on a specific URL, specifies that the server should respond to GET requests.) "GET" method accepts URL path as the first argument, and handler function as the second one. The function "(req, res) {...}"is the handler function. It takes two arguments: "req" (the request object) and "res" (the response object). The "req" object in Express represents the HTTP request and contains information about the incoming request, such as parameters, query strings, headers, and body data. On the other hand, the "res" object is the HTTP response object used to send data back to the client, allowing you to set headers, and status codes, and send the response data. To many words for me, because it's easier to remember after seeing code examples.

const express = require('express');
const app = express();
const PORT = 3000;
app.get('/', (req, res) => {
  res.send('Hello, Express!');
});


app.listen(PORT, () => {
  console.log(`Server is running on http://localhost:${PORT}`);
});

In our example, we send back a response short message, and also we should remember that we need to add a listener for events to our server. We added a listener to the Express instance and set the port there to 3000. So now we can open the browser window on the "localhost:3000" address and check the result.

Congratulations, it works perfectly!

In conclusion, this introductory dive into Express has laid a solid foundation for understanding the framework and creating a simple server. Express's versatility and ease of use have been highlighted, making it an ideal choice for developers aiming to build robust web applications and APIs.

In upcoming posts, we'll take our server to the next level, exploring more advanced functionalities, middleware implementation, database integration, and handling different HTTP methods. Join me as we continue to expand our Express server's capabilities and delve deeper into the intricacies of this powerful framework. Together, we'll explore new horizons and build upon the fundamentals to craft more sophisticated and feature-rich applications. Keep coding along!