# Setting Up Your First Node.js Application Step-by-Step

### **1\. Install Node.js**

Because Node.js is a runtime environment, you need to install it on your machine before you can execute any server-side JavaScript.

To keep things universally applicable regardless of whether you are using Windows, macOS, or Linux, the most straightforward approach is to use the official installers:

1.  Navigate to the official [**Node.js website**](https://nodejs.org/).
    
2.  You will see two download options. Always opt for the **LTS (Long Term Support)** version. It is the most stable release and is recommended for most users and production environments.
    
3.  Download the installer and follow the standard installation wizard prompts for your specific operating system. Leave the default settings checked—they include the Node package manager (npm), which you will need later**1\. Install Node.js**
    
    Because Node.js is a runtime environment, you need to install it on your machine before you can execute any server-side JavaScript.
    
    To keep things universally applicable regardless of whether you are using Windows, macOS, or Linux, the most straightforward approach is to use the official installers:
    
    1.  Navigate to the official [**Node.js website**](https://nodejs.org/).
        
    2.  You will see two download options. Always opt for the **LTS (Long Term Support)** version. It is the most stable release and is recommended for most users and production environments.
        
    3.  Download the installer and follow the standard installation wizard prompts for your specific operating system. Leave the default settings checked—they include the Node package manager (npm), which you will need later
        

### **2\. Checking the Installation**

Once the installation finishes, you need to verify that your operating system recognizes Node.js.

Open your system's terminal (Command Prompt or PowerShell on Windows, Terminal on macOS/Linux) and type the following command:

```shell
node -v
```

![](https://cdn.hashnode.com/uploads/covers/69501eadecd9fff694a8b6d8/a0a45d76-cefb-449c-9026-64773f29b005.png align="center")

You can also verify that npm was installed alongside Node by running:

```shell
npm -v
```

![](https://cdn.hashnode.com/uploads/covers/69501eadecd9fff694a8b6d8/5454f2ff-9ad3-4f1e-828b-2df2d255fa45.png align="center")

### **3\. Understanding the Node REPL**

Before writing a complete script, it's helpful to understand the **REPL**.

REPL stands for **Read-Eval-Print Loop**. It is an interactive, virtual environment directly in your terminal that takes a single JavaScript expression, evaluates it, prints the result, and loops back to wait for your next command. It is incredibly useful for quickly testing small snippets of logic or experimenting with built-in Node modules without needing to create a file.

To enter the REPL, simply type `node` into your terminal and hit Enter. Your prompt will change to a `>`.

Try typing a simple expression:

![](https://cdn.hashnode.com/uploads/covers/69501eadecd9fff694a8b6d8/bcba6109-633b-4178-89c0-12be323e4224.png align="center")

*(Note: The* `undefined` *appears because* `console.log()` *outputs the string but does not return a value).*

To exit the REPL, type `.exit` or press `Ctrl + C` twice.

###   
**4\. Creating Your First JavaScript File**

While the REPL is great for quick tests, real applications are written in files.

1.  Create a new folder on your machine named `node-starter` and open it in your preferred code editor.
    
2.  Inside this folder, create a new file named `app.js`.
    
3.  Add the following JavaScript code to the file and save it
    

```javascript
const greeting = "Hello World!";
console.log(greeting);
console.log("This script is running outside the browser.");
```

### **5\. Running the Script**

Now it is time to execute the file using the Node runtime.

Open your terminal, navigate to the `node-starter` folder you just created, and run the file by passing its name to the `node` command:

```shell
node app.js
```

When you run this command, Node.js takes your file, compiles the JavaScript into machine code using the V8 engine, and executes it directly on your system.

### **6\. Writing a "Hello World" Server**

Running a script in the terminal is the first step, but Node.js is famous for building web servers. Let's build a foundational server using **only** Node's built-in capabilities—no external frameworks required.

Create a new file named `server.js` and add the following code:

```javascript
const http = require('http');

const hostname = '127.0.0.1';
const port = 3000;

const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  
  res.end('Hello World! Your Node.js server is running.\n');
});

server.listen(port, hostname, () => {
  console.log(`Server running at http://\({hostname}:\){port}/`);
});
```

**To run your server:**

1.  In your terminal, execute the file:
    
    ```shell
    node server.js
    ```
    
2.  Your terminal will log: `Server running at [`[`http://127.0.0.1:3000/](http://127.0.0.1:3000/)`](http://127.0.0.1:3000/]\(http://127.0.0.1:3000/\)). The command prompt will hang because the server is now actively listening for requests.
    
3.  Open your web browser and navigate to [`http://localhost:3000`](http://localhost:3000). You will see your plain text response displayed on the screen.
    

To stop the server, go back to your terminal and press `Ctrl + C`.