Handling HTTP Requests
Write a basic Worker to intercept and respond to HTTP requests, demonstrating core functionality.
Handling HTTP Requests is a free Edge Computing with Cloudflare Workers & Deno lesson on CoddyKit — lesson 2 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Edge Computing with Cloudflare Workers & Deno learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Workers and Web Requests
Cloudflare Workers are powerful tools that sit at the edge of the internet. Think of them as highly efficient gatekeepers for your web traffic.
Their primary job is to intercept incoming HTTP requests, process them using your code, and then send back an appropriate HTTP response.
Understanding the Request
Every time a user's browser interacts with your Worker, it receives a Request object. This object is packed with all the details about the incoming request:
- URL: The full web address the user tried to reach.
- Method: The HTTP action, like GET (fetching data) or POST (sending data).
- Headers: Extra information such as the browser type, cookies, and preferred language.
- Body: Any data sent with the request, common with POST or PUT methods.
Catching the Fetch Event
Cloudflare Workers use an event listener to 'catch' incoming requests. The fetch event is triggered for every HTTP request that hits your Worker.
The standard entry point for a Worker is an exported object with an async fetch method. This method receives the request object as its first argument.
export default {
async fetch(request, env, ctx) {
// Your Worker logic goes here
// The 'request' object holds all incoming request details
return new Response("Hello from Worker!");
}
}Crafting a Simple Response
After your Worker processes a request, it needs to send back a Response object. This object contains the content and metadata that the user's browser will receive.
A basic Response can be created by simply passing a string of text to its constructor.
export default {
async fetch(request, env, ctx) {
const responseText = "Welcome to the edge!";
return new Response(responseText);
}
}Your First 'Hello Worker!'
Let's combine what we've learned to create a simple Worker that says "Hello Cloudflare Worker!" to every incoming request.
This is the fundamental structure you'll use for almost all Cloudflare Workers.
export default {
async fetch(request, env, ctx) {
return new Response("Hello Cloudflare Worker!");
}
}Peeking at the Request URL
You can access various properties of the request object to get information about the incoming request. For example, request.url gives you the full URL that was requested.
This allows you to create dynamic responses based on the specific path or query parameters a user is trying to reach.
export default {
async fetch(request, env, ctx) {
const url = request.url;
return new Response(`You requested: ${url}`);
}
}Responding to GET vs. POST
The request.method property tells you the HTTP method used (e.g., GET, POST, PUT, DELETE). You can use this to provide different logic for different types of requests.
For instance, a GET request might fetch data, while a POST request might submit data for creation.
export default {
async fetch(request, env, ctx) {
if (request.method === "GET") {
return new Response("This is a GET request.");
} else if (request.method === "POST") {
return new Response("This is a POST request.", { status: 201 });
}
return new Response("Method not allowed.", { status: 405 });
}
}Custom Headers and Status
You can customize the Response object further by adding HTTP headers or changing the status code. This is done by passing an options object as the second argument to the Response constructor.
- Headers: Provide metadata about the response (e.g.,
Content-Type: text/plain). - Status Code: Indicates the outcome of the request (e.g.,
200 OK,404 Not Found).
export default {
async fetch(request, env, ctx) {
return new Response("Custom response!", {
status: 200,
headers: {
"Content-Type": "text/plain",
"X-Worker-Info": "Processed at the Edge"
}
});
}
}Fetching from an Origin
Often, your Worker will act as a proxy. This means it fetches content from an 'origin server' (your actual website or API backend) and potentially modifies it before sending it to the user.
You can use the global fetch() function, passing it the original request object, to forward the request to another server.
export default {
async fetch(request, env, ctx) {
// Fetch the request from the origin server
const response = await fetch(request);
// You can modify the response here before returning it
return response;
}
}Worker Response Check
You're building a Cloudflare Worker. Which of the following correctly sets the status code of a response to 404 Not Found?
Recap: Handling HTTP Requests
In this lesson, you learned the core of Cloudflare Workers: how they handle HTTP requests and send back responses.
- Workers intercept
fetchevents. - The
Requestobject contains all incoming request data. - You return a
Responseobject to the user. - You can access request details like URL and method.
- Responses can have custom status codes and headers.
- Workers can act as proxies, fetching content from origin servers.
Next, you'll learn the steps to deploy your first Worker to Cloudflare's edge network so it can start serving users globally!
Frequently asked questions
Is the “Handling HTTP Requests” lesson free?
Yes — the full text of “Handling HTTP Requests” is free to read here on the web, and the Edge Computing with Cloudflare Workers & Deno course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Edge Computing with Cloudflare Workers & Deno course, upgrade to CoddyKit PRO.
What will I learn in “Handling HTTP Requests”?
Write a basic Worker to intercept and respond to HTTP requests, demonstrating core functionality. You practise Edge Computing with Cloudflare Workers & Deno with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Edge Computing with Cloudflare Workers & Deno?
No prior experience is required. Edge Computing with Cloudflare Workers & Deno on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Handling HTTP Requests” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Edge Computing with Cloudflare Workers & Deno lesson?
Yes. Every Edge Computing with Cloudflare Workers & Deno lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.