Building a chat application has always been an enticing project for developers looking to hone their skills and modernize their practices. In this article, we will explore how to quickly create a simple chat app using Deno Deploy, which promises high efficiency and ease of use for JavaScript and TypeScript developers. This solution leverages modern web technologies, including Oak for routing and Fresh for UI development.

What is Deno and Deno Deploy?

Deno is a secure runtime for JavaScript and TypeScript that has gained popularity as a new alternative to Node.js. It simplifies many aspects of the development process and improves performance through its built-in modules and TypeScript support without requiring a separate package manager.

Deno Deploy is a serverless platform that allows developers to deploy their applications directly to the edge, making them accessible globally with minimal latency. This makes Deno Deploy an excellent choice for quickly launching applications like our chat app.

Getting Started with Deno Installment

Before we dive into coding, ensure that you have Deno installed on your machine. If you’re using macOS, you can install it via Homebrew with this simple command:

brew install deno

Setting Up Our Chat Application

Step 1: Create the Project

1. Open your terminal and create a new project directory. For this example, we will name it deno_chat.

   mkdir deno_chat && cd deno_chat

2. Open the directory in your code editor (e.g., VS Code).
3. Initialize a git repository for version control:

git init

4. Create a subdirectory for your API server called deno_chat_api and add an index.js file. This file will serve as your starting point:

   mkdir deno_chat_api && touch deno_chat_api/index.js

Populate index.js with a simple response:

   addEventListener("fetch", (event) => {
       event.respondWith(new Response("Hello World"));
   });

Step 2: Deploy the API

Next, we will deploy our API to Deno Deploy:

1. Create a new repository on GitHub called deno_chat. Then add it as a remote in your local project:

git remote add origin <your_github_repo_url>

2. Commit your changes:

git add .
git commit -m "Initial commit"

3. Push the code to GitHub:

git push -u origin main

4. Visit the Deno Deploy website, sign up, and create a new project using the URL of your index.js file. It will generate a deployment URL for you.

Step 3: Incorporating Oak for Routing

While we now have a basic API, it lacks routing capabilities. To make our chat app functional, we’ll implement Oak, a middleware framework for Deno that provides a more complete server component.

1. Import Oak into your index.js file from a URL:

   import { Application, Router } from "https://deno.land/x/oak/mod.ts";

2. Set up the basic application structure with routing:

   const app = new Application();
   const router = new Router();

   router.get('/messages', (context) => {
       context.response.body = messages;
   });

   app.use(router.routes());
   app.use(router.allowedMethods());

   await app.listen({ port: 8000 });

3. Create an array to hold chat messages:

   const messages = [];

4. Update the code to handle incoming chat messages via POST request:

   router.post('/messages', async (context) => {
       const { value } = await context.request.body();
       messages.push(value);
       context.response.status = 201;
   });

5. Commit your changes, push them to GitHub, and check the updated deployment.

Step 4: Building the Frontend with Fresh

We now need a client-side application to, quite literally, chat with our API:

1. In your terminal, create a new directory for our client app using Fresh, the frontend framework for Deno:

   fresh init deno_chat_client

2. Inside the deno_chat_client directory, create components to display messages and an input box for new messages.
3. Use hooks to handle state for your messages and wire them up to post via the fetch API:

   const [messages, setMessages] = useState([]);

   const getMessages = async () => {
       const res = await fetch('/messages');
       setMessages(await res.json());
   };

   useEffect(() => {
       getMessages();
   }, []);

4. Deploy the client app similarly as you did with the API.

Step 5: Implementing Broadcast Communication

Finally, we can enhance our chat application with real-time communication via Broadcast Channels, which will allow different instances of your app to be synchronized:

1. Update your server to include the Broadcast Channel API:

   const channel = new BroadcastChannel('chat');
   channel.onmessage = (event) => {
       messages.push(event.data);
   };

   channel.postMessage(newMessage);

2. Make sure all nodes can synchronize their message lists through the same channel.
3. Commit changes, push to GitHub, and see it live on Deno Deploy.

Conclusion: Deploying Fast with Deno

From our exploration, building and deploying an application with Deno and Deno Deploy is seamless and straightforward. The combination of Deno, Oak, and Fresh offers a robust set of tools for developing modern web applications effortlessly.

With each change pushed to GitHub, we can redeploy with incredible speed, allowing for rapid development cycles. This makes Deno Deploy a compelling option for developers looking to utilize their JavaScript and TypeScript tooling in creating efficient cloud-based applications.

If you’re interested in learning more about Deno, cloud functions, or modern web development practices, follow the relevant communities and documentation. Furthermore, would you like to share your thoughts or insights? Feel free to comment below or reach out on social media!