Tags: javascript

1023

sparkline

Sunday, May 15th, 2022

Image previews with the FileReader API

I added a “notes” section to this website eight years ago. I set it up so that notes could be syndicated to Twitter. Ever since then, that’s the only way I post to Twitter.

A few months later I added photos to my notes. Again, this would get syndicated to Twitter.

Something’s bothered me for a long time though. I initially thought that if I posted a photo, then the accompanying text would serve as a decription of the image. It could effectively act as the alt text for the image, I thought. But in practice it didn’t work out that way. The text was often a commentary on the image, which isn’t the same as a description of the contents.

I needed a way to store alt text for images. To make it more complicated, it was possible for one note to have multiple images. So even though a note was one line in my database, I somehow needed a separate string of text with the description of each image in a single note.

I eventually settled on using the file system instead of the database. The images themselves are stored in separate folders, so I figured I could have an accompanying alt.txt file in each folder.

Take this note from yesterday as an example. Different sizes of the image are stored in the folder /images/uploaded/19077. Here’s a small version of the image and here’s the original. In that same folder is the alt text.

This means I’m reading a file every time I need the alt text instead of reading from a database, which probably isn’t the most performant way of doing it, but it seems to be working okay.

Here’s another example:

In order to add the alt text to the image, I needed to update my posting interface. By default it’s a little textarea, followed by a file upload input, followed by a toggle (a checkbox under the hood) to choose whether or not to syndicate the note to Twitter.

The interface now updates automatically as soon as I use that input type="file" to choose any images for the note. Using the FileReader API, I show a preview of the selected images right after the file input.

Here’s the code if you ever need to do something similar. I’ve abstracted it somewhat in that gist—you should be able to drop it into any page that includes input type="file" accept="image/*" and it will automatically generate the previews.

I was pleasantly surprised at how easy this was. The FileReader API worked just as expected without any gotchas. I think I always assumed that this would be quite complex to do because once upon a time, it was quite complex (or impossible) to do. But now it’s wonderfully straightforward. Story of the web.

My own version of the script does a little bit more; it also generates another little textarea right after each image preview, which is where I write the accompanying alt text.

I’ve also updated my server-side script that handles the syndication to Twitter. I’m using the /media/metadata/create method to provide the alt text. But for some reason it’s not working. I can’t figure out why. I’ll keep working on it.

In the meantime, if you’re looking at an image I’ve posted on Twitter and you’re judging me for its lack of alt text, my apologies. But each tweet of mine includes a link back to the original note on this site and you will most definitely find the alt text for the image there.

Wednesday, May 11th, 2022

The Demise of the Mildly Dynamic Website

It me:

Broadly, these are websites which are still web pages, not web applications; they’re pages of essentially static information, personal websites, blogs, and so on, but they are slightly dynamic. They might have a style selector at the top of each page, causing a cookie to be set, and the server to serve a different stylesheet on every subsequent page load.

This rings sadly true to me:

Suppose a company makes a webpage for looking up products by their model number. If this page were made in 2005, it would probably be a single PHP page. It doesn’t need a framework — it’s one SELECT query, that’s it. If this page were made in 2022, a conundrum will be faced: the company probably chose to use a statically generated website. The total number of products isn’t too large, so instead their developers stuff a gigantic JSON file of model numbers for every product made by the company on the website and add some client-side JavaScript to download and query it. This increases download sizes and makes things slower, but at least you didn’t have to spin up and maintain a new application server. This example is fictitious but I believe it to be representative.

Also, I never thought about “serverless” like this:

Recently we’ve seen the rise in popularity of AWS Lambda, a “functions as a service” provider. From my perspective this is literally a reinvention of CGI, except a) much more complicated for essentially the same functionality, b) with vendor lock-in, c) with a much more complex and bespoke deployment process which requires the use of special tools.

Wednesday, May 4th, 2022

Why I don’t miss React: a story about using the platform - Jack Franklin

This is a great case study of switching from a framework mindset to native browser technologies.

Though this is quite specific to Jack’s own situation, I do feel like there’s something in the air here. The native browser features are now powerful and stable enough to make the framework approach feel outdated.

And if you do want to use third-party dependencies, Jack makes a great case for choosing smaller single-responsibility helpers rather than monolithic frameworks.

Replacing lit-html would be an undertaking but much less so than replacing React: it’s used in our codebase purely for having our components (re)-render HTML. Replacing lit-html would still mean that we can keep our business logic, ultimately maintaining the value they provide to end-users. Lit-Html is one small Lego brick in our system, React (or Angular, or similar) is the entire box.

Tuesday, May 3rd, 2022

Bugblogging

A while back I wrote a blog post called Web Audio API weirdness on iOS. I described a bug in Mobile Safari along with a hacky fix. I finished by saying:

If you ever find yourself getting weird but inconsistent behaviour on iOS using the Web Audio API, this nasty little hack could help.

Recently Jonathan Aldrich posted a thread about the same bug. He included a link to my blog post. He also said:

Thanks so much for your post, this was a truly pernicious problem!

That warms the cockles of my heart. It’s very gratifying to know that documenting the bug (and the fix) helped someone out. Or, as I put it:

Yay for bugblogging!

Forgive the Germanic compound word, but in this case I think it fits.

Bugblogging doesn’t need to involve a solution. Just documenting a bug is a good thing to do. Recently I documented a bug with progressive web apps on iOS. Before that I documented a bug in Facebook Container for Firefox. When I documented some weird behaviour with the Web Share API in Safari on iOS, I wasn’t even sure it was a bug but Tess was pretty sure it was and filed a proper bug report.

I’ve benefited from other people bugblogging. Phil Nash wrote Service workers: beware Safari’s range request. That was exactly what I needed to solve a problem I’d been having. And then that post about Phil solving my problem helped Peter Rukavina solve a similar issue so he wrote Phil Nash and Jeremy Keith Save the Safari Video Playback Day.

Again, this warmed the cockles of my heart. Bugblogging is worth doing just for the reward of that feeling.

There’s a similar kind of blog post where, instead of writing about a bug, you write about a particular technique. In one way, this is the opposite of bugblogging because you’re writing about things working exactly as they should. But these posts have a similar feeling to bugblogging because they also result in a warm glow when someone finds them useful.

Here are some recent examples of these kinds of posts—tipblogging?—that I’ve found useful:

All three are very handy tips. Thanks, Eric! Thanks, Rich! Thanks, Stephanie!

Sunday, May 1st, 2022

Trust • Robin Rendle

Robin adds a long-zoom perspective on my recent post:

I am extremely confident that pretty much any HTML I write today will render the same way in 50 years’ time. How confident am I that my CSS will work correctly? Mmmm…70%. Hand-written JavaScript? Way less, maybe 50%. A third-party service I install on a website or link to? 0% confident. Heck, I’m doubtful that any third-party service will survive until next year, let alone 50 years from now.

Saturday, April 30th, 2022

Trust and suspicion | Keenan Payne

Another thoughtful reponse to my recent post.

Reflections on native browser features and third-party library adoption.

Thursday, April 28th, 2022

Suspicion

I’ve already had some thoughtful responses to yesterday’s post about trust. I wrapped up my thoughts with a request:

I would love it if someone could explain why they avoid native browser features but use third-party code.

Chris obliged:

I can’t speak for the industry, but I have a guess. Third-party code (like the referenced Bootstrap and React) have a history of smoothing over significant cross-browser issues and providing better-than-browser ergonomic APIs. jQuery was created to smooth over cross-browser JavaScript problems. That’s trust.

Very true! jQuery is the canonical example of a library smoothing over the bumpy landscape of browser compatibilities. But jQuery is also the canonical example of a library we no longer need because the browsers have caught up …and those browsers support standards directly influenced by jQuery. That’s a library success story!

Charles Harries takes on my question in his post Libraries over browser features:

I think this perspective of trust has been hammered into developers over the past maybe like 5 years of JavaScript development based almost exclusively on inequality of browser feature support. Things are looking good in 2022; but as recently as 2019, 4 of the 5 top web developer needs had to do with browser compatibility.

Browser compatibility is one of the underlying promises that libraries—especially the big ones that Jeremy references, like React and Bootstrap—make to developers.

So again, it’s browser incompatibilities that made libraries attractive.

Jim Nielsen responds with the same message in his post Trusting Browsers:

We distrust the browser because we’ve been trained to. Years of fighting browser deficiencies where libraries filled the gaps. Browser enemy; library friend.

For example: jQuery did wonders to normalize working across browsers. Write code once, run it in any browser — confidently.

Three for three. My question has been answered: people gravitated towards libraries because browsers had inconsistent implementations.

I’m deliberately using the past tense there. I think Jim is onto something when he says that we’ve been trained not to trust browsers to have parity when it comes to supporting standards. But that has changed.

Charles again:

This approach isn’t a sustainable practice, and I’m trying to do as little of it as I can. Jeremy is right to be suspicious of third-party code. Cross-browser compatibility has gotten a lot better, and campaigns like Interop 2022 are doing a lot to reduce the burden. It’s getting better, but the exasperated I-just-want-it-to-work mindset is tough to uninstall.

I agree. Inertia is a powerful force. No matter how good cross-browser compatibility gets, it’s going to take a long time for developers to shed their suspicion.

Jim is glass-half-full kind of guy:

I’m optimistic that trust in browser-native features and APIs is being restored.

He also points to a very sensible mindset when it comes to third-party libraries and frameworks:

In this sense, third-party code and abstractions can be wonderful polyfills for the web platform. The idea being that the default posture should be: leverage as much of the web platform as possible, then where there are gaps to creating great user experiences, fill them in with exploratory library or framework features (features which, conceivably, could one day become native in browsers).

Yes! A kind of progressive enhancement approach to using third-party code makes a lot of sense. I’ve always maintained that you should treat libraries and frameworks like cattle, not pets. Don’t get too attached. If the library is solving a genuine need, it will be replaced by stable web standards in browsers (again, see jQuery).

I think that third-party libraries and frameworks work best as polyfills. But the whole point of polyfills is that you only use them when the browsers don’t supply features natively (and you also go back and remove the polyfill later when browsers do support the feature). But that’s not how people are using libraries and frameworks today. Developers are reaching for them by default instead of treating them as a last resort.

I like Jim’s proposed design princple:

Where available, default to browser-native features over third party code, abstractions, or idioms.

(P.S. It’s kind of lovely to see this kind of thoughtful blog-to-blog conversation happening. Right at a time when Twitter is about to go down the tubes, this is a demonstration of an actual public square with more nuanced discussion. Make your own website and join the conversation!)

Wednesday, April 27th, 2022

Trust

I’ve noticed a strange mindset amongst front-end/full-stack developers. At least it seems strange to me. But maybe I’m the one with the strange mindset and everyone else knows something I don’t.

It’s to do with trust and suspicion.

I’ve made no secret of the fact that I’m suspicious of third-party code and dependencies in general. Every dependency you add to a project is one more potential single point of failure. You have to trust that the strangers who wrote that code knew what they were doing. I’m still somewhat flabbergasted that developers regularly add dependencies—via npm or yarn or whatever—that then pull in even more dependencies, all while assuming good faith and competence on the part of every person involved.

It’s a touching expression of faith in your fellow humans, but I’m not keen on the idea of faith-based development.

I’m much more trusting of native browser features—HTML elements, CSS features, and JavaScript APIs. They’re not always perfect, but a lot of thought goes into their development. By the time they land in browsers, a whole lot of smart people have kicked the tyres and considered many different angles. As a bonus, I don’t need to install them. Even better, end users don’t need to install them.

And yet, the mindset I’ve noticed is that many developers are suspicious of browser features but trusting of third-party libraries.

When I write and talk about using service workers, I often come across scepticism from developers about writing the service worker code. “Is there a library I can use?” they ask. “Well, yes” I reply, “but then you’ve got to understand the library, and the time it takes you to do that could be spent understanding the native code.” So even though a library might not offer any new functionality—just a different idion—many developers are more likely to trust the third-party library than they are to trust the underlying code that the third-party library is abstracting!

Developers are more likely to trust, say, Bootstrap than they are to trust CSS grid or custom properties. Developers are more likely to trust React than they are to trust web components.

On the one hand, I get it. Bootstrap and React are very popular. That popularity speaks volumes. If lots of people use a technology, it must be a safe bet, right?

But if we’re talking about popularity, every single browser today ships with support for features like grid, custom properties, service workers and web components. No third-party framework can even come close to that install base.

And the fact that these technologies have shipped in stable browsers means they’re vetted. They’ve been through a rigourous testing phase. They’ve effectively got a seal of approval from each individual browser maker. To me, that seems like a much bigger signal of trustworthiness than the popularity of a third-party library or framework.

So I’m kind of confused by this prevalent mindset of trusting third-party code more than built-in browser features.

Is it because of the job market? When recruiters are looking for developers, their laundry list is usually third-party technologies: React, Vue, Bootstrap, etc. It’s rare to find a job ad that lists native browser technologies: flexbox, grid, service workers, web components.

I would love it if someone could explain why they avoid native browser features but use third-party code.

Until then, I shall remain perplexed.

Wednesday, April 20th, 2022

Tuesday, April 12th, 2022

CSS Quick Tip: Animating in a newly added element | Stephanie Eckles

I can see myself almost certainly needing to use this clever technique at some point so I’m going to squirrel it away now for future me.

Wednesday, March 30th, 2022

Make Beautifully Resilient Apps With Progressive Enhancement

You had me at “beautifully resilient apps with progressive enhancement”.

This is a great clear walkthrough of enhancing a form submission. A lot of this seems like first principles to me, but if you’ve only ever built single page apps, then thinking about a server-submission process first might well be revelatory.

Sunday, March 13th, 2022

Make it boring — jlwagner.net

People are propelled by their interests, and web developers have a lot of space to be interested in all sorts of stuff. For you, it may be JavaScript ‘n Friends, or HTML and CSS. Maybe it’s all that stuff, but put aside your preferences for a moment and answer me this: what are you helping people to do? If the answer involves any remotely routine or crucial purpose, consider putting aside your personal desire for excitement. Instead, make boring things that are usable, accessible, and fast. Ours is a job done by people for people, not a glamorous rockstar gig.

Excellent advice from Jeremy who wants us to build fast, reliable, resilient websites …even if the technologies involved in doing that don’t feel exciting.

Central to that endeavor is recognizing that the browser gives you a ton of stuff for free. Relying on those freebies requires a willingness to not npm install a solution for every problem — especially those that are best solved with CSS and HTML. Those technologies may seem boring, but boring is fast. Boring is usable. Boring is resilient and fault tolerant. Boring is accessible. When we rely wholesale on JavaScript to build for the web, we’re inevitably reinventing things. At worst, our reinventions of rock-solid HTML features — such as client-side form validation  — break in unexpected ways despite our carefully written tests. At best, a flawless reimplementation of those features adds unnecessary code to applications, and depends on a technology less fault-tolerant than CSS and HTML.

Wednesday, March 9th, 2022

When should there be a declarative version of a JavaScript API?

I feel like it’s high time I revived some interest in my proposal for button type="share". Last I left it, I was gathering use cases and they seem to suggest that the most common use case for the Web Share API is sharing the URL of the current page.

If you want to catch up on the history of this proposal, here’s what I’ve previously written:

Remember, my proposal isn’t to replace the JavaScript API, it’s to complement it with a declarative option. The declarative option doesn’t need to be as fully featured as the JavaScript API, but it should be able to cover the majority use case. I think this should hold true of most APIs.

A good example is the Constraint Validation API. For the most common use cases, the required attribute and input types like “email”, “url”, and “number” have you covered. If you need more power, reach for the JavaScript API.

A bad example is the Geolocation API. The most common use case is getting the user’s current location. But there’s no input type="geolocation" (or button type="geolocation"). Your only choice is to use JavaScript. It feels heavy-handed.

I recently got an email from Taylor Hunt who has come up with a good litmus test for JavaScript APIs that should have a complementary declarative option:

I’ve been thinking about how a lot of recently-proposed APIs end up having to deal with what Chrome devrel’s been calling the “user gesture/activation budget”, and wondering if that’s a good indicator of when something should have been HTML in the first place.

I think he’s onto something here!

Think about any API that requires a user gesture. Often the documentation or demo literally shows you how to generate a button in JavaScript in order to add an event handler to it in order to use the API. Surely that’s an indication that a new button type could be minted?

The Web Share API is a classic example. You can’t invoke the API after an event like the page loading. You have to invoke the API after a user-initiated event like, oh, I don’t know …clicking on a button!

The Fullscreen API has the same restriction. You can’t make the browser go fullscreen unless you’re responding to user gesture, like a click. So why not have button type="fullscreen" in HTML to encapsulate that? And again, the fallback in non-supporting browsers is predictable—it behaves like a regular button—so this is trivial to polyfill. I should probably whip up a polyfill to demonstrate this.

I can’t find a list of all the JavaScript APIs that require a user gesture, but I know there’s more that I’m just not thinking of. I’d love to see if they’d all fit this pattern of being candidates for a new button type value.

The only potential flaw in this thinking is that some APIs that require a user gesture might also require a secure context (either being served over HTTPS or localhost). But as far as I know, HTML has never had the concept of features being restricted by context. An element is either supported or it isn’t.

That said, there is some prior art here. If you use input type="password" in a non-secure context—like a page being served over HTTP—the browser updates the interface to provide scary warnings. Perhaps browsers could do something similar for any new button types that complement secure-context JavaScript APIs.

Monday, March 7th, 2022

web-platform-tests dashboard

It’s great to see browsers working together to collectively implement a range of much-needed features.

These scores represent how browser engines are doing in 15 focus areas and 3 joint investigation efforts.

Saturday, March 5th, 2022

Progressive Enhancement, the New Hotness™ | Go Make Things

Here’s a great explanation of progressive enhancement, complete with practical examples and myth-busting. Pass it ‘round!

If you care about quality engineering, you want as much fault tolerance in the things you build as possible.

Thursday, February 24th, 2022

How to make MPAs that are as fast as SPAs | Go Make Things

The headline is a little misleading because if you follow this advice, your multi-page apps will be much much faster than single page apps, especially when you include that initial page load of a single page app.

Here’s a quick high-level summary of what I do…

  1. Serve pre-rendered, mostly static HTML.
  2. Inline everything, including CSS and JavaScript.
  3. Use mostly platform-native JavaScript, and as little of it as possible.
  4. Minify and gzip all the things.
  5. Lean heavily on service workers.

That’s an excellent recipe for success right there!

Tuesday, February 22nd, 2022

SPAs were a mistake | Go Make Things

Browsers give you a ton of stuff for free, built right in, out-of-the-box. SPAs break all that, and force you to recreate it yourself with JavaScript. Most developers do it wrong, and for the ones who do it right, it results in a ton of extra code to recreate features the browser already gave you for free.

Tuesday, February 15th, 2022

Canned web development — Jeremy Wagner

Our mental model for how we build for the web is too reliant on canned solutions to unique problems.

This is very perceptive indeed.

Compounding this problem is that too few boot camps are preparing new web developers to think critically about what problems are best solved by JavaScript and which aren’t — and that those problems that are best solved by JavaScript can be solved without engaging in frivolous framework whataboutism. The question developers should ask more often when grappling with framework shortcomings shouldn’t be “what about that other framework?”, but rather “what’s best for the user experience?”.

Wednesday, February 2nd, 2022

“Evergreen” Does Not Mean Immediately Available | CSS-Tricks - CSS-Tricks

Smart advice on future-proofing and backward-compatibility:

There isn’t a single, specific device, browser, and person we cater to when creating a web experience. Websites and web apps need to adapt to a near-infinite combination of these circumstances to be effective. This adaptability is a large part of what makes the web such a successful medium.

Consider doing the hard work to make it easy and never remove feature queries and @supports statements. This creates a robust approach that can gracefully adapt to the past, as well as the future.

Monday, January 31st, 2022

The baseline for web development in 2022

A thoroughly researched look at what our baseline criteria should be for making websites today:

The baseline for web development in 2022 is:

  • low-spec Android devices in terms of performance,
  • Safari from two years before in terms of Web Standards,
  • and 4G in terms of networks.

The web in general is not answering those needs properly, especially in terms of performance where factors such as an over-dependence on JavaScript are hindering our sites’ performance.

It’s somewhat damning to Safari to see it as a baseline browser, but with Internet Explorer out of the picture, something has to be the lowest common denominator. In this case, Safari is quite literally the new IE.