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May 21, 2019

Filed under: tech»web

Radios Hack

The past few months, I've mostly been writing in public for NPR's News Apps team blog, with posts on the new Dailygraphics rig (and setting it up on Windows), the Mueller report redactions, and building a scrolling audio story. However, in my personal time, I decided to listen to some podcasts. So naturally, I built a web-based listener app, just for me.

I had a few goals for Radio as I was building it. The first was my own personal use case, in which I wanted to track and listen to a few podcasts, but not actually install a dedicated player on my phone. A web app makes perfect sense for this kind of ephemeral use case, especially since I'm not ever really offline anymore. I also wanted to try building something entirely using Web Components instead of a UI framework, and to use modern features like import — in part because I wanted to see if I could recommend it as a standard workflow for younger developers, and for internal newsroom tools.

Was it a success? Well, I've been using it to listen to Waypoint and Says Who for the last couple of months, so I'd say on that metric it proved itself. And I certainly learned a lot. There are definitely parts of this experience that I can whole-heartedly recommend — importing JavaScript modules instead of using a bundler is an amazing experience, and is the right kind of tradeoff for the health of the open web. It's slower (equivalent to dynamic AMD imports) but fast enough for most applications, and it lets many projects opt entirely out of beginner-unfriendly tooling.

Not everything was as smooth. I'm on record for years as a huge fan of Web Components, particularly custom elements. And for an application of this size, it was a reasonably good experience. I wrote a base class that automated some of the rough edges, like templating and synchronizing element attributes and properties. But for anything bigger or more complex, there are some cases where the platform feels lacking — or even sometimes actively hostile.

For example: in the modern, V1 spec for custom elements, they're not allowed to manipulate their own contents until they've been placed in the page. If you want to skip the extra bookkeeping that would require, you are allowed to create a shadow root in the constructor and put whatever HTML you want inside. It feels very much like this is the workflow you're supposed to use. But shadow DOM is harder to inspect at the moment (browser tools tend to leave it collapsed when inspecting the page), and it causes problems with events (which do not cross the shadow DOM boundary unless you alter your dispatch code).

There's also no equivalent in Web Components for the state management that's core to most modern frameworks. If you want to pass information down to child components from the parent, it either needs to be set through attributes (meaning you only get strings) or properties (more bookkeeping during the render step). I suspect if I were building something larger than this simple list-of-lists, I'd want to add something like Redux to manage data. This would tie my components to that framework, but it would substantially clean up the code.

Ironically, the biggest hassle in the development process was not from a new browser feature, but from a very old one: while it's very easy to create an audio tag and set its source to any sound clip on the web, actually getting the list of audio files is often impossible, thanks to CORS. Most podcasts do not publish their episode feeds with the cross-origin header set, so the browser's security settings shut down the AJAX requests completely. It's wild that in 2019, there's still no good way to make a secure request (say, one that transmits no cookies or custom headers) to another domain. I ended up running the final app on Glitch, which provides basic Node hosting, so that I could deploy a simple proxy for feed data.

For me, the neat thing about this project was how it brought back the feeling of hackability on the web, something I haven't really felt since I first built Caret years ago. It's so easy to get something spun up this way, and that's a huge incentive for creating little personal apps. I love being able to make an ugly little app for myself in only a few hours, instead of needing to evaluate between a bunch of native apps run by people I don't entirely trust. And I really appreciated the ways that Glitch made that easy to do, and emphasized that in its design. It helps that podcasting, so far, is still a platform built on open web tech: XML and MP3. More of this, please!

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