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November 5, 2014

Filed under: journalism»new_media

Election Elements

You might have heard that there was an election this last week. Like every news organization, The Seattle Times had a live results page, powered by a Node-based scraper. It did pretty well: we had no glitches with pulling results, and the response has been solid. It also generated the source data for the print edition. Oh, and we put bunting on the front page, which is not something you get to do every day.

Behind the scenes, however, that results page has another interesting feature: as far as I'm aware, it's the first use of Web Components (at least, the custom elements part) in production by a news organization. Each of the Washington maps on the page is a custom-built <svg-map> element, which handles loading the image document and provides a set of convenience methods for manipulating the map once it's available.

SVG is one of those technologies that I really want to like, but has always been a total pain to actually use. It's an annoying format to author, doesn't seem to actually save any space compared to bitmap images, and has a ton of edge cases even in "standard" browsers (for example, Chrome will forget the state of an SVG document inside an object tag if that tag or its parents are set to display: none). Wrapping it up in a component that would manage its lifecycle and quirks for me just seemed like a no-brainer.

To create the component, I used Andrea Giammarchi's registerElement() shim instead of Polymer's polyfill layer — Giammarchi's script only shims the custom element portion of Web Components, but it works all the way back to IE9 and (more importantly) is only 2KB. On top of that, I used RSVP.js to create a quick shared cache for SVG source documents, ICanHaz for my templating, and a custom module called Savage to do SVG class/style manipulation.

From the outside, however, you don't need to know any of that. Instead, the interface is simple:

  1. Write a map element into the page, with a src attribute pointing to the SVG file you want to load. Put your tooltip template inside the tag.
  2. Attach callbacks to the element's ready promise to run code once the image is on the page.
  3. Use the eachPath method on the element to do painting, and set the onhover callback to pass in data for templating in the tooltip.
Using these maps, in other words, is basically just like using a regular element, if regular elements had a DOM API that wasn't written by psychopaths. All their complexity is tucked away inside, and what they present externally is clean, simple, and self-contained. The map element does 80% of what Pro Publica's Landline does, and I'd argue it does it better.

As a developer, I'm really excited by the potential of these new custom elements. Although I had used them at ArenaNet for building the new Guild Wars 2 trading post, those were used to create tight integration with the in-game interface, and only needed to work in a single browser. This is the first time I've used them in a wider ecosystem, and they worked like a charm.

But as a library consumer, and particularly as a harried newsroom dev, I think web components have a tremendous potential to make complex behavior way easier to build and train for. Take the afore-mentioned Landline, for example: wouldn't it be nice to simply include a script tag (or an HTML import) and then be able to write <landline-map> tags into the page, with an attribute pointing to a CSV or a Google Sheet containing the necessary data? Or consider Pym, NPR's responsive iframe library that's so great I forked and rewrote big chunks of it. Right now, using Pym on the parent page requires including the script, adding a dummy element, and then initializing the script — why shouldn't it just be <pym-embed> instead?

Distributing libraries not as modules or loose scripts, but as chunks of new HTML functionality, has the potential to radically change how we create new content on the web in the future. Newsrooms, which are always under pressure and often consume "pre-made" tools for interactive elements like timelines and galleries, are a perfect use-case for Web Components. After this election experience, I'm planning to lean heavily on them whenever possible, and I'm hoping other people will as well.

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