Build a React App

React is the most widely used JavaScript frontend framework.

In this tutorial we'll build a simple React app with Deno. The app will display a list of dinosaurs. When you click on one, it'll take you to a dinosaur page with more details.

View source.

Create a React app with Vite and Deno Jump to heading#

This tutorial will use Vite to quickly scaffold a Deno and React app. Vite is a build tool and development server for modern web projects. It pairs well with React and Deno, leveraging ES modules and allowing you to import React components directly.

In your terminal run the following command to create a new React app with Vite:

deno run --A npm:create-vite-extra

From the offered options select deno-react and typescript.

Then, cd into the newly created project folder and the following command to serve your new react app:

deno task dev

This will start the Vite server, click the output link to localhost to see your app in the browser.

Add a backend Jump to heading#

The next step is to add a backend API. We'll create a very simple API that returns information about dinosaurs.

In the root of your new project, create an api folder. In that folder, create a main.ts file, which will run the server, and a data.json, which will contain the hard coded dinosaur data.

Copy and paste this json file into the api/data.json file.

We're going to build out a simple API server with routes that return dinosaur information. We'll use the oak middleware framework and the cors middleware to enable CORS.

Use the deno add command to add the required dependencies to your project:

deno add @oak/oak @tajpouria/cors

Next, update api/main.ts to import the required modules and create a new Router instance to define some routes:

import { Application, Router } from "@oak/oak";
import data from "./data.json" with { type: "json" };

const router = new Router();

After this, in the same file, we'll define three routes. The first route at / will return the string Welcome to the dinosaur API, then we'll set up /api to return all the dinosaurs, and finally /api/:donosaur to return a specific dinosaur based on the name in the URL:

router
  .get("/", (context) => {
    context.response.body = "Welcome to dinosaur API!";
  })
  .get("/api", (context) => {
    context.response.body = data;
  })
  .get("/api/:dinosaur", (context) => {
    if (!context?.params?.dinosaur) {
      context.response.body = "No dinosaur name provided.";
    }

    const dinosaur = data.find((item) =>
      item.name.toLowerCase() === context.params.dinosaur.toLowerCase()
    );

    context.response.body = dinosaur ? dinosaur : "No dinosaur found.";
  });

Finally, at the bottom of the same file, create a new Application instance and attach the routes we just defined to the application using app.use(router.routes()) and start the server listening on port 8000:

const app = new Application();
app.use(oakCors());
app.use(router.routes());
app.use(router.allowedMethods());

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

You can run the API server with deno run --allow-env --allow-net api/main.ts. We'll create a task to run this command in the background and update the dev task to run both the React app and the API server.

In your deno.json file, update the tasks field to include the following:

{
  "tasks": {
    "dev": "deno task dev:api & deno task dev:vite",
    "dev:api": "deno run --allow-env --allow-net api/main.ts",
    "dev:vite": "deno run -A npm:vite"
    // ...
  }
}

If you run deno task dev now and visit localhost:8000, in your browser you should see the text Welcome to dinosaur API!, and if you visit localhost:8000/api, you should see a JSON response of all of the dinosaurs.

🦕 Lookin' good so far! Now lets build out the client side of the app.

Add a router Jump to heading#

The app will have two routes: / and /:dinosaur.

We'll use react-router-dom to build out some routing logic, so we'll need to add the react-router-dom dependency to your project. In the project root run:

deno add npm:react-router-dom

Update the /src/main.tsx file to import and use the BrowserRouter component from react-router-dom:

import React from "react";
import ReactDOM from "react-dom/client";
import App from "./App";
import { BrowserRouter } from "react-router-dom";
import "./index.css";

ReactDOM.createRoot(document.getElementById("root") as HTMLElement).render(
  <BrowserRouter>
    <App />
  </BrowserRouter>,
);

Create the routes and types Jump to heading#

We'll create two pages: Index and Dinosaur. The Index page will list all the dinosaurs and the Dinosaur page will show details of a specific dinosaur.

Create a pages folder in the src directory and inside that create two files: index.tsx and Dinosaur.tsx.

Types Jump to heading#

Both pages will use the Dino type to describe the shape of data they're expecting from the API, so let's create a types.ts file in the project root:

export type Dino = { name: string; description: string };

Index.tsx Jump to heading#

This page will fetch the list of dinosaurs from the API and render them as links:

import React, { useEffect, useState } from "react";
import { Link } from "react-router-dom";
import { Dino } from "../../types";

export default function () {
  const [dinosaurs, setDinosaurs] = useState<Dino[]>([]);

  useEffect(() => {
    (async () => {
      const response = await fetch(`http://localhost:8000/api/`);
      const allDinosaurs = await response.json() as Dino[];
      setDinosaurs(allDinosaurs);
    })();
  }, []);

  return (
    <div>
      <h1>Welcome to the Dinosaur app</h1>
      <p>Click on a dinosaur below to learn more.</p>
      {dinosaurs.map((dinosaur: Dino) => {
        return (
          <div key={dinosaur.name}>
            <Link to={`/${dinosaur.name.toLowerCase()}`}>{dinosaur.name}</Link>
          </div>
        );
      })}
    </div>
  );
}

Dinosaur.tsx Jump to heading#

This page will fetch the details of a specific dinosaur from the API and render it in a paragraph:

import React, { useEffect, useState } from "react";
import { Link, useParams } from "react-router-dom";
import { Dino } from "../../types";

export default function () {
  const { selectedDinosaur } = useParams();
  const [dinosaur, setDino] = useState<Dino>({ name: "", description: "" });

  useEffect(() => {
    (async () => {
      const resp = await fetch(`http://localhost:8000/api/${selectedDinosaur}`);
      const dino = await resp.json() as Dino;
      setDino(dino);
    })();
  }, []);

  return (
    <div>
      <h1>{dinosaur.name}</h1>
      <p>{dinosaur.description}</p>
      <Link to="/">See all</Link>
    </div>
  );
}

Update the App component to use the routes Jump to heading#

Finally, we can point to these two new pages in the src/App.tsx file:

import { Route, Routes } from "react-router-dom";
import Index from "./pages/index";
import Dinosaur from "./pages/Dinosaur";
import "./App.css";

function App() {
  return (
    <div>
      <Routes>
        <Route exact path="/" element={<Index />} />
        <Route exact path="/:selectedDinosaur" element={<Dinosaur />} />
      </Routes>
    </div>
  );
}

export default App;

Run the app Jump to heading#

To run the app use the task you set up earlier

deno task dev

Navigate to the local server in your browser and you should see the list of dinosaurs displayed which you can click through to find out about each one.

🦕 Now you can scaffold and develop a React app with Vite and Deno! You’re ready to build blazing-fast web applications. We hope you enjoy exploring these cutting-edge tools, we can't wait to see what you make!