CSS-driven console graphics

If you’re reading this post via my blog and using a desktop computer, try opening your browser’s debug console (don’t worry; I’ll wait). If you don’t know how, here’s instructions for Firefox and instructions for Chrome. Other browsers may vary. You ought to see something like this in your debugger:

Debug console on DanQ.me showing Dan's head and a speech bubble.
I’m in your console, eating your commands!

What sorcery is this?

The debug console is designed to be used by web developers so that they can write Javascript code right in their browser as well as to investigate any problems with the code run by a web page. The web page itself can also output to the console, which is usually used for what I call “hello-based debugging”: printing out messages throughout a process so that the flow and progress can be monitored by the developer without having to do “proper” debugging. And it gets used by some web pages to deliver secret messages to any of the site users who open their debugger.

Facebook console messaging advising against the use of the console.
Facebook writes to the console a “stop” message, advising against using the console unless you know what you’re doing in an attempt to stop people making themselves victims of console-based social engineering attacks.

Principally, though, the console is designed for textual content and nothing else. That said, both Firefox and Chrome’s consoles permit the use of CSS to style blocks of debug output by using the %c escape sequence. For example, I could style some of a message with italic text:

>> console.log('I have some %citalic %ctext', 'font-style: italic;', '');
   I have some italic text

Using CSS directives like background, then, it’s easy to see how one could embed an image into the console, and that’s been done before. Instead, though, I wanted to use the lessons I’d learned developing PicInHTML 8¾ years ago to use text and CSS (only) to render a colour picture to the console. First, I created my template image – a hackergotchi of me and an accompanying speech bubble, shrunk to a tiny size and posterised to reduce the number of colours used and saved as a PNG.

Hackergotchi of Dan with a speech bubble, "squashed".
The image appears “squashed” to compensate for console monospace letters not being “square”.

Next, I wrote a quick Ruby program, consolepic.rb, to do the hard work. It analyses each pixel of the image and for each distinct colour assigns to a variable the CSS code used to set the background colour to that colour. It looks for “strings” of like pixels and combines them into one, and then outputs the Javascript necessary to write out all of the above. Finally, I made a few hand-tweaks to insert the text into the speech bubble.

The resulting output weighs in at 31.6kB – about a quarter of the size of the custom Javascript on the frontend of my site and so quite a bit larger than I’d have liked and significantly less-efficient than the image itself, even base64-encoded for embedding directly into the code, but that really wasn’t the point of the exercise, was it? (I’m pretty sure there’s significant room for improvement from a performance perspective…)

Scatmania.org in 2012
I’ll be first to admit it’s not as cool as the “pop-up Dan” in the corner of my 2012 design. You might enjoy my blog post about my 20 years of blogging or the one about how “pop-up Dan” worked.

What it achieved was an interesting experiment into what can be achieved with Javascript, CSS, the browser console, and a little imagination. An experiment that can live here on my site, for anybody who looks in the direction of their debugger, for the foreseeable future (or until I get bored of it). Anybody with any more-exotic/silly ideas about what this technique could be used for is welcome to let me know!


I’ve recently been reimplementing retro arcade classic Pong to show off during a celebration of World Digital Preservation Day 2018 yesterday at the Bodleian Libraries. Here’s how that went down.

Frak on the BBC Micro, amongst the rest of a pile of computing nostalgia
The Bodleian has a specific remit for digital archiving… but sometimes they just like collecting stuff, too, I’m sure.

The team responsible for digital archiving had plans to spend World Digital Preservation Day running a stand in Blackwell Hall for some time before I got involved. They’d asked my department about using the Heritage Window – the Bodleian’s 15-screen video wall – to show a carousel of slides with relevant content over the course of the day. Or, they added, half-jokingly, “perhaps we could have Pong up there as it’ll be its 46th birthday?”

Parts of the Digital Archiving display table
Free reign to play about with the Heritage Window while smarter people talk to the public about digital archives? Sure, sign me up.

But I didn’t take it as a joke. I took it as a challenge.

Emulating Pong is pretty easy. Emulating Pong perfectly is pretty hard. Indeed, a lot of the challenge in the preservation of (especially digital) archives in general is in finding the best possible compromise in situations where perfect preservation is not possible. If these 8″ disks are degrading, is is acceptable to copy them onto a different medium? If this video file is unreadable in modern devices, is it acceptable to re-encode it in a contemporary format? These are the kinds of questions that digital preservation specialists have to ask themselves all the damn time.

Pong prototype with a SNES controller on my work PC
The JS Gamepad API lets your web browser talk to controller devices.

Emulating Pong in a way that would work on the Heritage Window but be true to the original raised all kinds of complications. (Original) Pong’s aspect ratio doesn’t fit nicely on a 16:9 widescreen, much less on a 27:80 ultrawide. Like most games of its era, the speed is tied to the clock rate of the processor. And of course, it should be controlled using a “dial”.

By the time I realised that there was no way that I could thoroughly replicate the experience of the original game, I decided to take a different track. Instead, I opted to reimplement Pong. A reimplementation could stay true to the idea of Pong but serve as a jumping-off point for discussion about how the experience of playing the game may be superficially “like Pong” but that this still wasn’t an example of digital preservation.

Two participants play Pong on the Heritage Window
Bip… boop… boop… bip… boop… bip…

Here’s the skinny:

  • A web page, displayed full-screen, contains both a <canvas> (for the game, sized appropriately for a 3 × 3 section of the video wall) and a <div> full of “slides” of static content to carousel alongside (filling a 2 × 3 section).
  • Javascript writes to the canvas, simulates the movement of the ball and paddles, and accepts input from the JS Gamepad API (which is awesome, by the way). If there’s only one player, a (tough! – only three people managed to beat it over the course of the day!) AI plays the other paddle.
  • A pair of SNES controllers adapted for use as USB controllers which I happened to own already.
My Javascript-powered web applications dominate the screens in Blackwell Hall.
Increasingly, the Bodleian’s spaces seem to be full of screens running Javascript applications I’ve written.

I felt that the day, event, and game were a success. A few dozen people played Pong and explored the other technology on display. Some got nostalgic about punch tape, huge floppy disks, and even mechanical calculators. Many more talked to the digital archives folks and I about the challenges and importance of digital archiving. And a good time was had by all.

I’ve open-sourced the entire thing with a super-permissive license so you can deploy it yourself (you know, on your ultrawide video wall) or adapt it as you see fit. Or if you’d just like to see it for yourself on your own computer, you can (but unless you’re using a 4K monitor you’ll probably need to use your browser’s mobile/responsive design simulator set to 3200 × 1080 to make it fit your screen). If you don’t have controllers attached, use W/S to control player 1 and the cursor keys for player 2 in a 2-player game.

Happy 46th birthday, Pong.

When to use CSS vs. JavaScript

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by an author

CSS before JS #

My general rule of thumb is…

If something I want to do with JavaScript can be done with CSS instead, use CSS.

CSS parses and renders faster.

For things like animations, it more easily hooks into the browser’s refresh rate cycle to provide silky smooth animations (this can be done in JS, too, but CSS just makes it so damn easy).

And it fails gracefully.

A JavaScript error can bring all of the JS on a page to screeching halt. Mistype a CSS property or miss a semicolon? The browser just skips the property and moves on. Use an unsupported feature? Same thing.

This exactly! If you want progressive enhancement (and you should), performance, and the cleanest separation of behaviour and presentation, the pages you deliver to your users (regardless of what technology you use on your server) should consist of:

  • HTML, written in such a way that that they’re complete and comprehensible alone – from an information science perspective, your pages shouldn’t “need” any more than this (although it’s okay if they’re pretty ugly without any more)
  • CSS, adding design, theme, look-and-feel to your web page
  • Javascript, using progressive enhancement to add functionality in-the-browser (e.g. validation on the client-side in addition to the server side validation, for speed and ease of user experience) and, where absolutely necessary, to add functionality not possible any other way (e.g. if you’re looking to tap into the geolocation API, you’re going to need Javascript… but it’s still desirable to provide as much of the experience as possible without)

Developers failing to follow this principle is making the Web more fragile and harder to archive. It’s not hard to do things “right”: we just need to make sure that developers learn what “right” is and why it’s important.

Incidentally, I just some enhancements to the header of this site, including some CSS animations on the logo and menu (none of them necessary, but all useful) and some Javascript to help ensure that users of touch-capable devices have an easier time. Note that neither Javascript nor CSS are required to use this site; they just add value… just the way the Web ought to be (where possible).

Push without notifications

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On the first day of Indie Web Camp Berlin, I led a session on going offline with service workers. This covered all the usual use-cases: pre-caching; custom offline pages; saving pages for offline reading.

But on the second day, Sebastiaan spent a fair bit of time investigating a more complex use of service workers with the Push API.

While I’m very unwilling to grant permission to be interrupted by intrusive notifications, I’d be more than willing to grant permission to allow a website to silently cache timely content in the background. It would be a more calm technology.

Then when I’m on a plane, or in the subway, or in any other situation without a network connection, I could still visit these websites and get content that’s fresh to me. It’s kind of like background sync in reverse.

Yes, yes, yes.The Push API’s got incredible potential for precaching, or even re-caching existing content. How about if you could always instantly open my web site, whether you were on or off-line, and know that you’d always be able to read the front page and most-recent articles. You should be able to opt-in to “hot” push notifications if that’s what you really want, but there should be no requirement to do so.

By the time you’re using the Push API for things like this, why not go a step further? How about PWA feed readers or email clients that use web-pushes to keep your Inbox full? What about social network clients that always load instantly with the latest content? Or even analytics packages to push your latest stats to your device? Or turn-based online games that push the latest game state, ready for you to make your next move (which can be cached offline and pushed back when online)?

There are so many potential uses for “quiet” pushing, and now I’m itching for an opportunity to have a play with them.

The thing about ad-blocker popups

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I’ve been, in the past, a firm distruster of ad blocking software. I still am, to a large extent. I don’t trust any company whose finance model is based on inserting exceptions for advertisers they like. But I installed Ghostery, whose model is to use the stats of what gets blocked to offer consultancy to companies to make their adverts less horrific. I like this idea, so I support it. My Ghostery install is fairly open, blocking only sites that offer page-takeover, popups, autoplaying videos, and other stuff that annoys me a lot. So I get a bit annoyed when I’m scrolling through a Wired article and get something like this:

Fine. I don’t disagree with the sentiment, but I don’t read Wired often enough to care about being a member, so yeah, ad supported isn’t unreasonable. Do you know what’s unreasonable, Wired? This is what happens when I whitelist your site:

I’ve gone full-nuclear these last few years and I just keep Javascript disabled for most domains, most of the time (I’m using uMatrix). The Web is a lot faster, for it, and I can just enable it for domains that “need” it as-and-when. I also keep a userscript to-hand that I can tweak as-and-when to block anti-ad-blocker scripts, so that enabling Javascript on your domain (but not the domains of your dozen trackers/advertisers) doesn’t mean that I see your anti-ad-blocker popups either.

If your site nags gently (e.g. by mentioning where ads would be that they’re blocked, perhaps with a sad face emoticon) I’ll consider adding the ads, if your site has value. But more likely, if your site’s good, I’ll be looking for the donate link. You can make more money out of me with donations than you ever would be showing me ads: I’m more than happy to pay for the Web… I’m not happy to have 75% of the work my computer does when I’m reading your content be about your advertising partners tracking me nor about trying to “block” me from seeing your content.

The full article helps show how bad the Web’s gotten. When it starts to get better again, perhaps I’ll stop blocking ads and trackers so aggressively.

Salty JavaScript analogy

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JavaScript is like salt. If you add just enough salt to a dish, it’ll help make the flavour awesome. Add too much though, and you’ll completely ruin it.

Similarly, if you add just enough JavaScript to your website, it’ll help make it awesome. Add too much though, and you’ll completely ruin it.

This, this, a thousand times this.

What’s The Longest Word You Can Write With Seven-Segment Displays?

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From now on, when I try to engage junior programmers with the notion that they should make use of their general-purpose computers to answer questions for them… no matter how silly the question?… I’ll show them this video. It’s a moderately-concise explanation of the thought processes and programming practice involved in solving a simple, theoretical problem, and it does a great job at it.

How Much of My Graticule is Covered With Water?

I’m a moderately-keen geohasher, as you might be aware if you follow my geohashing logs or you saw that video of me going ‘hashing earlier this month.

For those that don’t know, the skinny version is this: in May 2008 an XKCD comic was published proposing (or at least joking about) a new game with a name reminiscient of geocaching. To play the game, participants use a mathematical hashing function on the current date and the most recent Dow Jones Industrial Average opening value to generate sets of random coordinates around the globe and then try to find their way to them, hopefully experiencing adventures along the way. The nature of stock markets and hashing functions means that the coordinates for any given day are effectively random and impossible to predict (far) in advance, so it’s sometimes described as a spontaneous adventure generator.

XKCD comic #426, "Geohashing"
The XKCD comic that started it all.

Recently, I found myself wondering about how much of a disadvantage players are at if they live in very “wet” graticules. Residents of the Channel Islands graticule (49 -2), for example, are confined to two land masses surrounded entirely by water. And while it’s true that water hashpoints can be visited if you’re determined enough, it’s still got to be considered to be playing at a disadvantage compared to those of us lucky ones in landlocked graticules like mine (51 -1).

And because I’m me and so can’t comfortably leave a question unanswered, I wrote a program to try to answer it! It’s among the hackiest, dirtiest software solutions I’ve ever written, so if it works for you then it’s a flipping miracle. What it does is:

  1. Determines which OpenStreetMap tiles (the image files served to your browser when you use OpenStreetMap) cover the graticule in question, and downloads them.
  2. Extracts information about the colour of each pixel in each tile.
  3. Counts the proportion of “water blue” pixels to other pixels (this isn’t perfect, because it trips over things like ferry lines on the map as being “not water”, especially at low zoom-levels).
Extreme zoom-in on Worcester College Lake, on OpenStreetMap.
Some parts of Worcester College Lake are identified as “not water” on account of the text overlay.

I mentioned it was hacky, right?

You can try it for yourself, if you’d like. You’ll need NodeJS, wget, wc, and ImageMagick – all pretty standard or easy-to-get things on a typical Linux box. Run with node geohash-pcwater.js 51 -1, where 51 -1 is the identifier for the graticule you’re interested in. And in case you’re interested – the Swindon graticule (where I live) is about 0.68% water, but the Channel Islands graticule is closer to 93.13% water. That’s no small disadvantage: sorry, Channel Islands geohashers!

Update 2018-08-22: discovered some prior art that takes a somewhat-similar approach.

The Bullshit Web

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The Bullshit Web (pxlnv.com)
My home computer in 1998 had a 56K modem connected to our telephone line; we were allowed a maximum of thirty minutes of computer usage a day, because my parents — quite reasonably — did not want to have their telephone shut off for an evening at a time. I remember webpages loading slowly: ten […]

My home computer in 1998 had a 56K modem connected to our telephone line; we were allowed a maximum of thirty minutes of computer usage a day, because my parents — quite reasonably — did not want to have their telephone shut off for an evening at a time. I remember webpages loading slowly: ten to twenty seconds for a basic news article.

At the time, a few of my friends were getting cable internet. It was remarkable seeing the same pages load in just a few seconds, and I remember thinking about the kinds of the possibilities that would open up as the web kept getting faster.

And faster it got, of course. When I moved into my own apartment several years ago, I got to pick my plan and chose a massive fifty megabit per second broadband connection, which I have since upgraded.

So, with an internet connection faster than I could have thought possible in the late 1990s, what’s the score now? A story at the Hill took over nine seconds to load; at Politico, seventeen seconds; at CNN, over thirty seconds. This is the bullshit web.

But first, a short parenthetical: I’ve been writing posts in both long- and short-form about this stuff for a while, but I wanted to bring many threads together into a single document that may pretentiously be described as a theory of or, more practically, a guide to the bullshit web.

A second parenthetical: when I use the word “bullshit” in this article, it isn’t in a profane sense. It is much closer to Harry Frankfurt’s definition in “On Bullshit”:

It is just this lack of connection to a concern with truth — this indifference to how things really are — that I regard as of the essence of bullshit.

I also intend it to be used in much the same sense as the way it is used in David Graeber’s “On the Phenomenon of Bullshit Jobs”:

In the year 1930, John Maynard Keynes predicted that, by century’s end, technology would have advanced sufficiently that countries like Great Britain or the United States would have achieved a 15-hour work week. There’s every reason to believe he was right. In technological terms, we are quite capable of this. And yet it didn’t happen. Instead, technology has been marshaled, if anything, to figure out ways to make us all work more. In order to achieve this, jobs have had to be created that are, effectively, pointless. Huge swathes of people, in Europe and North America in particular, spend their entire working lives performing tasks they secretly believe do not really need to be performed. The moral and spiritual damage that comes from this situation is profound. It is a scar across our collective soul. Yet virtually no one talks about it.


These are what I propose to call ‘bullshit jobs’.

What is the equivalent on the web, then?

This, this, a thousand times this. As somebody who’s watched the Web grow both in complexity and delivery speed over the last quarter century, it apalls me that somewhere along the way complexity has started to win. I don’t want to have to download two dozen stylesheets and scripts before your page begins to render – doubly-so if those additional files serve no purpose, or at least no purpose discernable to the reader. Personally, the combination of uMatrix and Ghostery is all the adblocker I need (and I’m more-than-willing to add a little userscript to “fix” your site if it tries to sabotage my use of these technologies), but when for whatever reason I turn these plugins off I feel like the Web has taken a step backwards while I wasn’t looking.

Lunar Lander

Just want to play my game without reading this whole post? Play the game here – press a key, mouse button, or touch the screen to fire the thrusters, and try to land at less than 4 m/s with as much fuel left over as possible.

In 1969, when all the nerds were still excited by sending humans to the moon instead of flinging cars around the sun, the hottest video game was Rocket (or Lunar) for the PDP-8. Originally implemented in FOCAL by high school student Jim Storer and soon afterwards ported to BASIC (the other dominant language to come as standard with microcomputers), Rocket became the precursor to an entire genre of video games called “Lunar Lander games“.

Source code of Rocket and sample output.
Like many pieces of microcomputer software of the time, Rocket was distributed as printed source code that you’d need to carefully type in at the other end.

The aim of these games was to land a spacecraft on the moon or similar body by controlling the thrust (and in some advanced versions, the rotation) of the engine. The spacecraft begins in freefall towards the surface and will accelerate under gravity: this can be counteracted with thrust, but engaging the engine burns through the player’s limited supply of fuel. Furthermore, using fuel lowers the total mass of the vessel (a large proportion of the mass of the Apollo landers was fuel for use in the descent stage) which reduces its inertia, giving the engine more “kick” which must be compensated for during the critical final stages. It sounds dry and maths-y, but I promise that graphical versions can usually be played entirely “by eye”.

Atari's Lunar Lander (1979)
Atari’s 1979 adaptation is perhaps the classic version you’d recognise, although its release was somewhat overshadowed by their other vector-graphics space-themed release in 1979: Asteroids.

Let’s fast-forward a little. In 1997 I enrolled to do my A-levels at what was then called Preston College, where my Computing tutor was a chap called Kevin Geldard: you can see him at 49 seconds into this hilariously low-fi video which I guess must have been originally shot on VHS despite being uploaded to YouTube in 2009. He’s an interesting chap in his own right whose contributions to my career in computing deserve their own blog post, but for the time being all you need to know is that he was the kind of geek who, like me, writes software “for fun” more often than not. Kevin owned a Psion 3 palmtop – part of a series of devices with which I also have a long history and interest – and he taught himself to program OPL by reimplementing a favourite game of his younger years on it: his take on the classic mid-70s-style graphical Lunar Lander.

Psion Series 3
I never owned a Psion Series 3 (pictured), but I bought a Series 5mx in early 2000 out of my second student loan cheque, ultimately wrote most of my undergraduate dissertation using it, and eventually sold it to a collector in about 2009 for almost as much as I originally paid for it. The 5mx was an amazing bit of kit. But I’ll blog about that another day, I guess.

My A-level computing class consisted of a competitive group of geeky lads, and we made sort-of a personal extracurricular challenge to ourselves of re-implementing Kevin’s take on Lunar Lander using Turbo Pascal, the primary language in which our class was taught. Many hours out-of-class were spent in the computer lab, tweaking and comparing our various implementations (with only ocassional breaks to play Spacy, CivNet, or my adaptation of LORD2): later, some of us would extend our competition by going on to re-re-implement in Delphi, Visual Basic, or Java, or by adding additional levels relating to orbital rendezvous or landing on other planetary bodies. I was quite proud of mine at the time: it was highly-playable, fun, and – at least on your first few goes – moderately challenging.

Dan's Lunar Lander (2018)
I sometimes wonder what it would have looked like if I’d have implemented my 1997 Lunar Lander today. So I did.

Always game to try old new things, and ocassionally finding time between the many things that I do to code, I decided to expand upon my recently-discovered interest in canvas coding to bring back my extracurricular Lunar Lander game of two decades ago in a modern format. My goals were:

  • A one-button version of a classic “straight descent only” lunar lander game (unlike my 1997 version, which had 10 engine power levels, this remake has just “on” and “off”)
  • An implementation based initially on real physics (although not necessarily graphically to scale)… and then adapted as necessary to give a fun/playability balance that feels good
  • Runs in a standards-compliant browser without need for plugins: HTML5, Canvas, Javascript
  • Adapts gracefully to any device, screen resolution, and orientation with graceful degredation/progressive enhancement

You can have a go at my game right here in your web browser! The aim is to reach the ground travelling at a velocity of no more than 4 m/s with the maximum amount of fuel left over: this, if anything, is your “score”. My record is 52% of fuel remaining, but honestly anything in the 40%+ range is very good. Touch the screen (if it’s a touchscreen) or press a mouse button or any key to engage your thrusters and slow your descent.

End point of Dan's Lunar Lander (2018)
“Houston, the Eagle has landed.” Kerbal Space Program, it isn’t. Here’s a very good landing: 3 m/s with 48% of the fuel tank remaining.

And of course it’s all open-source, so you’re more than welcome to take it, rip it apart, learn from it, or make something better out of it.

How it feels to learn JavaScript in 2016

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How it feels to learn JavaScript in 2016 – Hacker Noon (hackernoon.com)

No JavaScript frameworks were created during the writing of this article.

The following is inspired by the article “It’s the future” from Circle CI. You can read the original here. This piece is just an opinion, and like any JavaScript framework, it shouldn’t be taken too seriously.

Hey, I got this new web project, but to be honest I haven’t coded much web in a few years and I’ve heard the landscape changed a bit. You are the most up-to date web dev around here right?

-The actual term is Front End engineer, but yeah, I’m the right guy. I do web in 2016. Visualisations, music players, flying drones that play football, you name it. I just came back from JsConf and ReactConf, so I know the latest technologies to create web apps.

Cool. I need to create a page that displays the latest activity from the users, so I just need to get the data from the REST endpoint and display it in some sort of filterable table, and update it if anything changes in the server. I was thinking maybe using jQuery to fetch and display the data?

-Oh my god no, no one uses jQuery anymore. You should try learning React, it’s 2016.

Oh, OK. What’s React?

A year or two old, and I’d love to claim that things were better in Javascript-framework-land today… but they’re not.