After upgrading to React 18, I ran into an issue where a Transition component would never reach the exited state. Specifically it happens when navigating to a new route whose components were loaded using Suspense and React.lazy.

As is typical, I found someone else facing a very similar issue, but no workaround or fix was posted.

For me the answer was to give the Transition component a unique key prop, e.g.

const Example = () => {
  // Pull a key from Reach Router
  const { key } = useLocation();

  return (
    <Transition
      key={key} 
      // etc...

Et voila! The transitions work properly again.

I have a React app which makes use of react-signature-pad-wrapper (which is a React wrapper for signature_pad). My component needs to call a function whenever someone stops drawing on the canvas. Until recently, I could use the onEnd event like so:

const signaturePadOptions = {
  minWidth: 1,
  maxWidth: 5,
  penColor: "rgb(0, 0, 0)",
  // This part doesn't work anymore:
  onEnd: handleEndStroke, 
}

Whenever the onEnd event was fired, my handleEndStroke function was called. But that changed in version 4 of signature-pad: Now we have to listen for endStroke events on the signaturePad. I’ve used the useEffect hook with addEventListener in my React component:

useEffect(() => {
  const handleEndStroke = () => {
    // I do my custom stuff here
  };

  if (!!ref.current && !!ref.current.signaturePad) {
    const current = ref.current;
    // initiate the event handler
    current.signaturePad.addEventListener(
      "endStroke",
      handleEndStroke,
      false
    );
    // clean up the event handler
    return function cleanup() {
      current.signaturePad.removeEventListener(
        "endStroke",
        handleEndStroke
      );
    };
  }
}, [ref]);

I have a React app (built with create-react-app) which I’m hosting on Cloudflare pages. I wanted to add a X-Robots-Tag HTTP header to every page on the site. It turns out to be really quite easy:

Create a new file called _headers in your public folder, and put this inside:

/*
  X-Robots-Tag: noindex, nofollow  

Obviously this is a really simple use-case, but there’s a lot more you can do. Headers take the following format:

[url]
  [name]: [value]

You can have multiple name/value pairs under a given URL. URLs can contain placeholders and wildcards (called “splats”) to help widen or narrow down where they apply. So to stop anything in the /app folder from being shown in an iframe you might do:

/app/*
  X-Frame-Options: DENY

You can set multiple headers for the same URL, e.g.

/app/*
  X-Frame-Options: SAMEORIGIN
  Referrer-Policy: same-origin
  X-Content-Type-Options: nosniff

Lets say your production site is on a custom domain, and the dev/test versions live on Cloudflare’s pages.dev domain. You don’t want search engines to index your dev/test versions, so you can send the X-Robots-Tag header only on those domains, using the placeholder functionality:

# Swap projectname below for your own project's name
https://:projectname.pages.dev/*
  X-Robots-Tag: noindex, nofollow  

There’s more examples over in their documentation.

I’m investigating Cloudflare Pages as a hosting platform for static sites and React SPAs (amongst other things).

My first impression: This is a really simple tool which handles almost everything about hosting for me. I’m practically sold already. Hook it up to your Github (or Gitlab) repository and for the most part, everything else happens automagically. That simplicity does come with limitations though, so it might not suit everybody.

Custom domains

Hooking up a custom domain to your CF Pages site is really simple. It’s completely automated if Cloudflare manages your DNS. If not, it’s just a case of adding a CNAME entry wherever your DNS is managed. So if I wanted to point sub.example.com to my CF pages site at example.pages.dev, i’d deploy this CNAME record:

NAME	TYPE	VALUE
sub.example.com	CNAME	example.pages.dev

I was also able to point a custom domain at the latest deployment from a specific Git branch, in this case the develop branch:

NAME	TYPE	VALUE
sub-develop.example.com	CNAME	develop.example.pages.dev

Environments and Previews

CF Pages can be a bit limiting if you have multiple deployment environments (e.g. development, staging, production). You can only have two sets of environment variables – one for Production and another for everything else. If you need more than that, you might want to look elsewhere for now. Luckily, it’s enough for me (for now).

Speaking of environment variables, at present you have to set them using their web interface, instead of a config file. I don’t have many, so it’s not an issue for me – but if your app makes heavy use of them, they might become a bit cumbersome to manage.

With all that said, CF Pages generates a preview build for every commit you push to Github. This is useful for getting someone else to test your work before merging it, and may reduce the need for different environments. Even if you don’t use CF Pages as your main hosting platform, the preview builds are a useful way to test your site before you go to production.

Workers and server-side code

I haven’t gotten into it yet, but CF Pages now integrates with CF Workers, which is their variant on Cloud Functions / Lambda / Serverless. You also get access to KV, their key-value data store. This means Cloudflare Pages doesn’t just need to be for static sites – there’s potentially a lot more flexibility available.

Other limitations and known issues

Handily, Cloudflare have documented some of the known issues and limitations of CF Pages.

When working in React SPAs, I tend to use named exports for the most part, e.g.

export const ProductList = () => {
  return <>A product list component</>;
}

And then, in another file…

import { ProductList } from "components/ProductList";

Part of this is is personal preference. It’s also down to my tooling: Flow’s autoimports feature seems to work best with named exports.

I usually only use default exports when creating screens or pages. This comes down to code splitting: I often lazy-load a screen when the user first navigates to it, and React.lazy presently only works with default exports. e.g.

const Products = () => (
  <>
    <h1>Products</h1>
    <ProductList />
  </>
);

export default Products;

And then in another file…

const Products = React.lazy(() => import("./screens/Products");
const Dashboard = React.lazy(() => import("./screens/Dashboard");

const Home = () => {
  return (
    <Router>
      <Route path="/products" component={Products} />
      <Route default component={Dashboard} /> 
    </Router>
  );
};

As part of my work, I sometimes I need to redirect links to a local installation of a web app, so I can debug a particular issue.

For example, I might receive an email with a link to https://test.example.com/what/ever?thing=stuff but I want to see what happens with the code running at http://localhost:3000/what/ever?thing=stuff. For a while I’ve been copying the link, pasting it, manually editing it, and carrying on. But I thought there had to be a better way.

It turns out Einar Egilsson’s Redirector extension is a better way. Install it in your browser (Firefox is my daily driver) and add a redirect like so:

Include Pattern: https://test.example.com/*
Redirect to: http://localhost:3000/$1

So when the redirect is enabled, any links to https://test.example.com will be redirected to localhost:3000. Thank you, Einar!

The Bavarian state court in Munich, Germany, on 20 January 2022, decided that using Google fonts in your site breaches the GDPR.

Ton Zijlstra (via Adactio)