NodeJs Tutorial

Last modified on: October 24, 2024

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<h3>Node.js Tutorial: Getting Started with Server-Side JavaScript</h3>
<p>Node.js is a powerful platform built on Chrome's V8 JavaScript engine, allowing you to execute JavaScript on the server. It is designed to build scalable, fast, and efficient web applications, handling multiple requests simultaneously without blocking the main thread. This tutorial will guide you through the fundamentals of Node.js, from installation to creating a simple server.</p>
<hr />
<h3>1. <strong>Installing Node.js and NPM</strong></h3>
<p>To get started, you&rsquo;ll need to install Node.js on your machine. Node.js comes with NPM (Node Package Manager), which helps you manage packages and libraries for your projects.</p>
<h4>Steps:</h4>
<ul>
<li><strong>Windows / macOS / Linux:</strong>
<ul>
<li>Visit the <a target="_new" rel="noopener">Node.js website</a> and download the latest stable version.</li>
<li>Run the installer and follow the instructions.</li>
<li>To verify the installation, open a terminal or command prompt and run the following commands:
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<pre class="language-markup"><code>node -v
npm -v</code></pre>
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</li>
<li>You should see the version numbers of both Node.js and NPM.</li>
</ul>
</li>
</ul>
<hr />
<h3>2. <strong>Creating Your First Node.js Application</strong></h3>
<p>Let&rsquo;s start by creating a simple Node.js application that sets up a basic HTTP server and responds with "Hello, World!".</p>
<h4>Steps:</h4>
<ol>
<li>
<p>Create a new directory for your project:</p>
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<pre class="language-javascript"><code>mkdir my-first-node-app
cd my-first-node-app</code></pre>
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</li>
<li>
<p>Initialize a Node.js project:</p>
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<pre class="language-javascript"><code>npm init -y</code></pre>
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<p>This command generates a <code>package.json</code> file, which contains information about your project and its dependencies.</p>
</li>
<li>
<p>Create a new file named <code>app.js</code> in your project folder.</p>
</li>
<li>
<p>Write the following code inside <code>app.js</code> to create an HTTP server:</p>
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<pre class="language-javascript"><code>// Import the HTTP module
const http = require('http');

// Create a server object
const server = http.createServer((req, res) =&gt; {
    res.writeHead(200, { 'Content-Type': 'text/html' });
    res.write('Hello, World!');
    res.end();
});

// The server listens on port 3000
server.listen(3000, () =&gt; {
    console.log('Server running on http://localhost:3000');
});</code></pre>
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</li>
<li>
<p>To run the server, use the following command:</p>
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<pre class="language-javascript"><code>node app.js</code></pre>
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<li>
<p>Open your browser and navigate to <code>http://localhost:3000</code>. You should see the message "Hello, World!".</p>
</li>
</ol>
<ol>
<li>
<p>&nbsp;</p>
</li>
</ol>
<hr />
<h3>3. <strong>Understanding Modules and NPM</strong></h3>
<p>Node.js has a modular architecture, and you can import different modules (either built-in or third-party) to extend its functionality.</p>
<h4>Built-In Modules:</h4>
<ul>
<li><strong><code>fs</code>:</strong> File system operations</li>
<li><strong><code>http</code>:</strong> Create HTTP servers</li>
<li><strong><code>path</code>:</strong> Handle file paths</li>
<li><strong><code>os</code>:</strong> Get information about the operating system</li>
</ul>
<p>Here&rsquo;s an example of reading a file with the <code>fs</code> module:</p>
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<pre class="language-javascript"><code>const fs = require('fs');

fs.readFile('example.txt', 'utf8', (err, data) =&gt; {
    if (err) throw err;
    console.log(data);
});</code></pre>
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<h4>Using NPM Packages:</h4>
<p>You can install third-party modules using NPM. For example, to install the popular <code>express</code> framework, you can run:</p>
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<pre class="language-javascript"><code>npm install express
</code></pre>
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<p>Here&rsquo;s how to create a basic Express app:</p>
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<pre class="language-javascript"><code>const express = require('express');
const app = express();

// Define a route
app.get('/', (req, res) =&gt; {
    res.send('Hello from Express!');
});

// Start the server
app.listen(3000, () =&gt; {
    console.log('Express server running on http://localhost:3000');
});</code></pre>
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<h3>5. <strong>Working with the File System</strong></h3>
<p>Node.js allows you to interact with the file system to read, write, or delete files using the built-in <code>fs</code> module.</p>
<h4>Reading a File:</h4>
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<pre class="language-javascript"><code>const fs = require('fs');

fs.readFile('example.txt', 'utf8', (err, data) =&gt; {
    if (err) throw err;
    console.log(data);
});</code></pre>
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<h4>Writing to a File:</h4>
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<pre class="language-javascript"><code>const fs = require('fs');

fs.writeFile('output.txt', 'Hello, Node.js!', (err) =&gt; {
    if (err) throw err;
    console.log('File has been saved!');
});</code></pre>
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<h3>6. <strong>Node.js with Databases</strong></h3>
<p>Node.js can interact with various databases like MySQL, MongoDB, or PostgreSQL. Let&rsquo;s look at an example using MongoDB with the <code>mongoose</code> package.</p>
<h4>Steps:</h4>
<ol>
<li>
<p>Install <code>mongoose</code>:</p>
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<pre class="language-javascript"><code>npm install mongoose</code></pre>
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</li>
<li>
<p>Connect to a MongoDB database:</p>
</li>
</ol>
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<pre class="language-javascript"><code>const mongoose = require('mongoose');

mongoose.connect('mongodb://localhost:27017/mydatabase', { useNewUrlParser: true, useUnifiedTopology: true });

const db = mongoose.connection;
db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', () =&gt; {
    console.log('Connected to MongoDB');
});</code></pre>
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<ol start="3">
<li>Define a schema and a model:</li>
</ol>
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<pre class="language-javascript"><code>const userSchema = new mongoose.Schema({
    name: String,
    age: Number
});

const User = mongoose.model('User', userSchema);

// Create a new user
const user = new User({ name: 'John', age: 30 });
user.save().then(() =&gt; console.log('User saved!'));</code></pre>
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<h3>7. <strong>Conclusion</strong></h3>
<p>Node.js is an incredibly powerful tool for building fast and scalable web applications. It allows you to use JavaScript on the server-side, making full-stack development more streamlined. With an active ecosystem and vast library of modules, Node.js is an excellent choice for developing everything from RESTful APIs to real-time applications like chat apps.</p>
<p>As you continue learning Node.js, explore more advanced topics such as:</p>
<ul>
<li>Working with WebSockets for real-time communication</li>
<li>Using asynchronous programming (promises, async/await)</li>
<li>Building RESTful APIs with Express</li>
<li>Implementing authentication and authorization</li>
</ul>
<p>This tutorial should have given you a good foundation to get started building applications in Node.js.</p>
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