Basic Request Handling

This guide walks you through creating your first Fastro application. You'll build a simple web server that responds with "Hello, World!" and learn the core concepts along the way.

Quick Start

Here's the complete code for your first Fastro application:

import fastro from "https://fastro.deno.dev/mod.ts";

// Create a new Fastro instance
const f = new fastro();

// Define a GET route that returns a greeting
f.get("/", () => "Hello, World!");

// Start the server on port 8000
await f.serve();

Step-by-Step Breakdown

Let's build this application step by step:

1. Import Fastro

import fastro from "https://fastro.deno.dev/mod.ts";

This imports the Fastro framework directly from the CDN. No package manager needed!

2. Create an Application Instance

const f = new fastro();

This creates a new Fastro application instance that will handle your routes and server configuration.

3. Define Your First Route

f.get("/", () => "Hello, World!");

This creates a GET route for the root path (/). When someone visits your website, they'll see "Hello, World!".

4. Start the Server

await f.serve();

This starts the HTTP server. By default, it listens on port 8000.

Running the Application

1. Save the code to a file named app.ts

2. Run with Deno:

   deno run --allow-net app.ts

   Note: The --allow-net flag is required to allow network access.

3. Open your browser and navigate to http://localhost:8000

You should see "Hello, World!" displayed in your browser! 🎉

Understanding the Code

Testing Your Server

You can test your server using different methods:

Using curl:

curl http://localhost:8000
# Output: Hello, World!

Using browser developer tools:

• Open Network tab
• Navigate to http://localhost:8000
• Check the response

Common Issues

Permission Denied

If you see a permission error, make sure you're using the --allow-net flag:

deno run --allow-net app.ts

Port Already in Use

If port 8000 is busy, specify a different port:

await f.serve({ port: 3000 });

Import Error

Ensure you have an internet connection to download the Fastro module from the CDN.

Next Steps

Congratulations! You've created your first Fastro application. Here's what to explore next:

• Request Context - Learn to handle request data and parameters
• Routing - Discover advanced routing patterns
• Middleware - Add functionality with middleware
• Templates - Render dynamic HTML responses

Quick Reference

// Different response types
f.get("/text", () => "Plain text");
f.get("/json", () => ({ message: "JSON response" }));
f.get("/html", () => "<h1>HTML response</h1>");

// Custom port
await f.serve({ port: 3000 });

// Custom hostname
await f.serve({ hostname: "0.0.0.0", port: 8000 });

Ready to build something more complex? Continue to Request Context to learn about handling user input and dynamic responses.