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Udibo React App

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A React Framework for Deno that makes it easy to create highly interactive apps that have server side rendering with file based routing for both your UI and API.

Apps are created using React Router, React Helmet Async, and Oak.


  • TypeScript out of the box
  • File-system routing like Next.js, Remix and Fresh for both your application’s UI and API
  • Nested routes
  • Server side rendering
  • Easy to extend
  • Error boundaries that work both on the server and in the browser
  • Quick builds with hot reloading
  • Can run on the edge with Deno Deploy


This module has 2 entry points.

  • mod.tsx: For use in code that will be used both on the server and in the browser.
  • server.tsx: For use in code that will only be used on the server.

You can look at the examples and deno docs to learn more about usage.


This repository contains one example for manually testing changes. To use it as the base for a new project, you would need to update the import_map.json file and deno.jsonc file to use udibo_react_app from the registry. The deno task commands in deno.jsonc would need to also use your import_map.json.

  • Example: A basic example of a Udibo React App.

The following examples are forks of the first example. They demonstate how easy it is to extend Udibo React Apps. The file in each of them describes how it was done.


To run the tests, use deno task test or deno task test-watch.

To check formatting and run lint, use deno task check.

To create a build and to run the build, use deno task build and deno task run. By default, the application builds and runs in development mode. To build and run a production build, set the APP_ENV environment variable to production.

To run the application in development mode with live reloading, use deno task dev.

When in development, identifiers are not minified and sourcemaps are generated and linked.


The GitHub workflows in this project can be used to run the tests and deploy your project. You can look at the examples to see how it is done.

If you don’t plan on using Deno Deploy to host your App, you can base your own deployment workflow on the deploy workflow in this repository.


React Helmet Async is used to manage all of your changes to the document head. You can add a Helmet tag to any page that you would like to update the document head.

  • Supports all valid head tags: title, base, meta, link, script, noscript, and style tags.
  • Supports attributes for body, html and title tags.

The following example can be found in the main route of the example in this repository. The Helmet in the main route of a directory will apply to all routes within the directory.

import { Helmet } from "npm/react-helmet-async";
// ...
  titleTemplate="Example | %s"
  htmlAttributes={{ lang: "en" }}
  <meta charSet="utf-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />

More examples of Helmet tag usage can be found in the React Helmet Reference Guide.


Udibo React Apps have 2 types of routes, UI Routes and API Routes. UI Routes that do not have an API Route with the same path will default to rendering the application on the server. The naming convention is the same for both types of routes.

In each directory within the routes directory, the main and index files have a special purpose. Neither the main or index file are required.

For the UI routes:

  • The index.tsx or index.jsx file’s react component will be used for requests to the directory.
  • The main.tsx or main.tsx file’s react component will be used as a wrapper around all routes in the directory. This can be useful for updating the head for all routes in the directory.

For the API routes:

  • The index.ts or index.js file will be used for requests to the directory.
  • The main.ts or main.js file will be used before all routes in the directory. This can be useful for adding middleware to all routes in the directory.

UI routes

All tsx/jsx files in your routes directory will be treated as UI routes. They should have a React component as their default export.

It’s recommended to use React Router components and hooks for navigation within your app. Udibo React App uses Router Components to connect all your routes together.

Parameterized routes can be created by wrapping your parameter name in brackets. For example, /blog/[id].tsx would handle requests like /blog/123, setting the id paramter to "123". The parameters can be accessed using the React Router useParams hook.

A wildcard route that will catch all requests that didn’t have any other matches can be created by naming a React file [...].tsx. The key for the parameter will be “*” and can be accessed the same way as named parameters.

API routes

All ts/js files in your routes directory will be treated as API routes. They should have an Oak router as their default export.

If you create an API route that relates to a UI route, it should call to render the app on the server. The render function will render the application as a readable stream and respond to the client with it.

Parameterized and wildcard routes work just like they do for UI routes. But the parameters are stored on the context’s params property. The key for wildcard parameters will be “0”.

import { Router } from "x/oak/mod.ts";
import { AppState } from "x/udibo_react_app/app_server.tsx";

export default new Router<AppState>()
  .get("/", async (context) => {
    const { state, params } = context;

Error handling

There are 2 ways to add error handling to your UI routes.

The easiest way is to add an ErrorFallback export to your UI Route. The related API router will automatically have error boundary middleware added to it, that will match the route path. For example, the /blog/[id] route would have the error’s boundary identifier set to "/blog/[id]". Then the AppErrorBoundary added around your component will have a matching boundary identifier.

If you’d like to nest an error boundary within your UI route component, you can use AppErrorBoundary or withAppErrorBoundary. If you do it this way, you will need to add errorBoundary middleware to your router to ensure any errors in that route are associated with the AppErrorBoundary you added.

const router = new Router()

Then the related UI route component needs to either use withAppErrorBoundary or AppErrorBoundary to be able to catch the error during rendering. The boundary identifier must match the one on the server.

const MyComponentSafe = withAppErrorBoundary(MyComponent, {
  FallbackComponent: DefaultErrorFallback,
  boundary: "MyComponentErrorBoundary",
  <MyComponent />

Ignore files

You can have the build script ignore files in your routes directory by adding an underscore prefix to their name.

Build artifacts

The only reserved file names are _main.ts and _main.tsx at the root of your routes directory. Those files are generated during the build process.

  • _main.ts: Exports an Oak router that connects all the Oak router files together.
  • _main.tsx: Exports a React Router route object that connects all your React component files together.

Import map

Deno has support for npm modules, however deno deploy doesn’t yet. Because of that, the import map currently imports all npm modules from To ensure all npm dependencies are using the same version of react, they need to have their version pinned. Once Deno Deploy has npm support, I’ll switch from using to npm specifier imports.

Disabling server side rendering

All pages will be rendered server side by default. If you have a component you don’t want to render on the server, you can disable it by having it return the fallback on the server. You can use isServer() to determine if the code is running on the server or in the browser. For example, in example/routes/blog, you could have it only get the post when rendering in the browser by setting post to undefined when on the server like shown below.

const post = isServer() ? undefined : getPost(id);
return post
  ? (
        <meta name="description" content={post.content} />
  : (

The actual example currently does render the post on the server.

Server side rendering with data fetching

To render a route that loads data on the server, you can add a matching Oak router that will cache the information being fetched before rendering the application. The example in this repository uses the AppContext to store the cached responses but that’s not the only way to do it. It’s recommended that you use a library like React Query to get your data.


To contribute, please read the contributing instruction.