Tags: performance

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Saturday, April 11th, 2020

Jeremy Keith ‘We’ve ruined the Web. Here’s how we fix it.’ - This is HCD

Did you hear the one about two Irishmen on a podcast?

I really enjoyed this back-and-forth discussion with Gerry on performance, waste, and more. We agreed on much, but we also clashed sometimes.

Monday, April 6th, 2020

Performance, security, and ethics: influencing effectively

I wrote something recently about telling the story of performance. Sue Loh emphasis the importance of understanding what makes people tick:

Performance engineers need to be an interesting mix of data-lovers and people-whisperers.

Friday, April 3rd, 2020

Responsive Images the Simple Way - Cloud Four

A nice succint explanation of using the srcset and sizes attributes on the img element—remember, you probably don’t need picture and source elements if your use case is swapping out different sized versions of the same image.

One caveat thought: you do need to know the dimensions of the images. If you’re dealing with unknown or user-generated photos, that can be an issue.

Thursday, March 26th, 2020

Let a website be a worry stone. — Ethan Marcotte

It was a few years before I realized that worry stones had a name, that they were borrowed from cultures other and older than mine. Heck, it’s been more than a few years since I’ve even held one. But in the last few weeks, before and after launching the redesign, I’ve kept working away at this website, much as I’d distractedly run my fingers over a smooth, flat stone.

Tuesday, March 24th, 2020

BBC - Future Media Standards & Guidelines - Accessibility Guidelines v2.0

A timely reminder:

The minimum dependency for a web site should be an internet connection and the ability to parse HTML.

Oh, embed!

I wrote yesterday about how messing about on your own website can be a welcome distraction. I did some tinkering with adactio.com on the weekend that you might be interested in.

Let me set the scene…

I’ve started recording and publishing a tune a day. I grab my mandolin, open up Quicktime and make a movie of me playing a jig, a reel, or some other type of Irish tune. I include a link to that tune on The Session and a screenshot of the sheet music for anyone who wants to play along. And I embed the short movie clip that I’ve uploaded to YouTube.

Now it’s not the first time I’ve embedded YouTube videos into my site. But with the increased frequency of posting a tune a day, the front page of adactio.com ended up with multiple embeds. That is not good for performance—my Lighthouse score took quite a hit. Worst of all, if a visitor doesn’t end up playing an embedded video, all of the markup, CSS, and JavaScript in the embedded iframe has been delivered for nothing.

Meanwhile over on The Session, I’ve got a strategy for embedding YouTube videos that’s better for performance. Whenever somebody posts a link to a video on YouTube, the thumbnail of the video is embedded. Only when you click the thumbnail does that image get swapped out for the iframe with the video.

That’s what I needed to do here on adactio.com.

First off, I should explain how I’m embedding things generally ‘round here. Whenever I post a link or a note that has a URL in it, I run that URL through a little PHP script called getEmbedCode.php.

That code checks to see if the URL is from a service that provides an oEmbed endpoint. A what-Embed? oEmbed!

oEmbed is like a minimum viable read-only API. It was specced out by Leah and friends years back. You ping a URL like this:

http://example.com/oembed?url=https://example.com/thing

In this case http://example.com/oembed is the endpoint and url is the value of a URL from that provider. Here’s a real life example from YouTube:

https://www.youtube.com/oembed?url=https://www.youtube.com/watch?v=-eiqhVmSPcs

So https://www.youtube.com/oembed is the endpoint and url is the address of any video on YouTube.

You get back some JSON with a pre-defined list of values like title and html. That html payload is the markup for your embed code.

By default, YouTube sends back markup like this:

<iframe
width="480"
height="270"
src="https://www.youtube.com/embed/-eiqhVmSPcs?feature=oembed"
frameborder="0
allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture"
allowfullscreen>
</iframe>

But now I want to use an img instead of an iframe. One of the other values returned is thumbnail_url. That’s the URL of a thumbnail image that looks something like this:

https://i.ytimg.com/vi/-eiqhVmSPcs/hqdefault.jpg

In fact, once you know the ID of a YouTube video (the ?v= bit in a YouTube URL), you can figure out the path to multiple images of different sizes:

(Although that last one—maxresdefault.jpg—might not work for older videos.)

Okay, so I need to extract the ID from the YouTube URL. Here’s the PHP I use to do that:

parse_str(parse_url($url, PHP_URL_QUERY), $arguments);
$id = $arguments['v'];

Then I can put together some HTML like this:

<div>
<a class="videoimglink" href="'.$url.'">
<img width="100%" loading="lazy"
src="https://i.ytimg.com/vi/'.$id.'/default.jpg"
alt="'.$response['title'].'"
srcset="
https://i.ytimg.com/vi/'.$id.'/mqdefault.jpg 320w,
https://i.ytimg.com/vi/'.$id.'/hqdefault.jpg 480w,
https://i.ytimg.com/vi/'.$id.'/maxresdefault.jpg 1280w
">
</a>
</div>

Now I’ve got a clickable responsive image that links through to the video on YouTube. Time to enhance. I’m going to add a smidgen of JavaScript to listen for a click on that link.

Over on The Session, I’m using addEventListener but here on adactio.com I’m going to be dirty and listen for the event directly in the markup using the onclick attribute.

When the link is clicked, I nuke the link and the image using innerHTML. This injects an iframe where the link used to be (by updating the innerHTML value of the link’s parentNode).

onclick="event.preventDefault();
this.parentNode.innerHTML='<iframe src=https://www.youtube-nocookie.com/embed/'.$id.'?autoplay=1></iframe>'"

But notice that I’m not using the default YouTube URL for the iframe. That would be:

https://www.youtube.com/embed/-eiqhVmSPcs

Instead I’m swapping out the domain youtube.com for youtube-nocookie.com:

https://www.youtube-nocookie.com/embed/-eiqhVmSPcs

I can’t remember where I first came across this undocumented parallel version of YouTube that has, yes, you guessed it, no cookies. It turns out that, not only is the default YouTube embed code bad for performance, it is—unsurprisingly—bad for privacy too. So the youtube-nocookie.com domain can protect your site’s visitors from intrusive tracking. Pass it on.

Anyway, I’ve got the markup I want now:

<div>
<a class="videoimglink" href="https://www.youtube.com/watch?v=-eiqhVmSPcs"
onclick="event.preventDefault();
this.parentNode.innerHTML='<iframe src=https://www.youtube-nocookie.com/embed/-eiqhVmSPcs?autoplay=1></iframe>'">
<img width="100%" loading="lazy"
src="https://i.ytimg.com/vi/-eiqhVmSPcs/default.jpg"
alt="The Banks Of Lough Gowna (jig) on mandolin"
srcset="
https://i.ytimg.com/vi/-eiqhVmSPcs/mqdefault.jpg 320w,
https://i.ytimg.com/vi/-eiqhVmSPcs/hqdefault.jpg 480w,
https://i.ytimg.com/vi/-eiqhVmSPcs/maxresdefault.jpg 1280w
">
</a>
</div>

The functionality is all there. But I want to style the embedded images to look more like playable videos. Time to break out some CSS (this is why I added the videoimglink class to the YouTube link).

.videoimglink {
    display: block;
    position: relative;
}

I’m going to use generated content to create a play button icon. Because I can’t use generated content on an img element, I’m applying these styles to the containing .videoimglink a element.

.videoimglink::before {
    content: '▶';
}

I was going to make an SVG but then I realised I could just be lazy and use the unicode character instead.

Right. Time to draw the rest of the fucking owl:

.videoimglink::before {
    content: '▶';
    display: inline-block;
    position: absolute;
    background-color: var(--background-color);
    color: var(--link-color);
    border-radius: 50%;
    width: 10vmax;
    height: 10vmax;
    top: calc(50% - 5vmax);
    left: calc(50% - 5vmax);
    font-size: 6vmax;
    text-align: center;
    text-indent: 1vmax;
    opacity: 0.5;
}

That’s a bunch of instructions for sizing and positioning. I’d explain it, but that would require me to understand it and frankly, I’m not entirely sure I do. But it works. I think.

With a translucent play icon positioned over the thumbnail, all that’s left is to add a :hover style to adjust the opacity:

.videoimglink:hover::before,
.videoimglink:focus::before {
    opacity: 0.75;
}

Wheresoever thou useth :hover, thou shalt also useth :focus.

Okay. It’s good enough. Ship it!

The Banks Of Lough Gowna (jig) on mandolin

If you embed YouTube videos on your site, and you’d like to make them more performant, check out this custom element that Paul made: Lite YouTube Embed. And here’s a clever technique that uses the srcdoc attribute to get a similar result (but don’t forget to use the youtube-nocookie.com domain).

Monday, March 23rd, 2020

Maintaining Performance - daverupert.com

In my experience, 99% of the time Web Performance boils down to two problems:

  1. “You wrote too much JavaScript.”
  2. “You have unoptimized images.”

But as Dave points out, the real issue is this:

I find that Web Performance isn’t particularly difficult once you understand the levers you can pull; reduce kilobytes, reduce requests, unblock rendering, defer scripts. But maintaining performance that’s a different story entirely…

Get Static – Eric’s Archived Thoughts

Performance matters …especially when the chips are down:

If you are in charge of a web site that provides even slightly important information, or important services, it’s time to get static. I’m thinking here of sites for places like health departments (and pretty much all government services), hospitals and clinics, utility services, food delivery and ordering, and I’m sure there are more that haven’t occurred to me. As much as you possibly can, get it down to static HTML and CSS and maybe a tiny bit of enhancing JS, and pare away every byte you can.

Tuesday, March 10th, 2020

Lighthouse bookmarklet

I use Firefox. You should too. It’s fast, secure, and more privacy-focused than the leading browser from the big G.

When it comes to web development, the CSS developer tooling in Firefox is second-to-none. But when it comes to JavaScript and network-related debugging (like service workers), Chrome’s tools are currently better than Firefox’s (for now). For example, Chrome has a tab in its developer tools that lets you run Lighthouse on the currently open tab.

Yesterday, I got the Calibre newsletter, which always has handy performance-related links from Karolina. She pointed to a Lighthouse extension for Firefox. “Excellent!”, I thought, and I immediately installed it. But I had some qualms about installing a plug-in from Google into a browser from Mozilla, particularly as the plug-in page says:

This is not a Recommended Extension. Make sure you trust it before installing

Well, I gave it a go. It turns out that all it actually does is redirect to the online version of Lighthouse. “Hang on”, I thought. “This could just be a bookmarklet!”

So I immediately uninstalled the browser extension and made this bookmarklet:

Lighthouse

Drag that up to your desktop browser’s bookmarks toolbar. Press it whenever you’re on a site that you want to test.

Tuesday, March 3rd, 2020

Telling the story of performance

At Clearleft, we’ve worked with quite a few clients on site redesigns. It’s always a fascinating process, particularly in the discovery phase. There’s that excitement of figuring out what’s currently working, what’s not working, and what’s missing completely.

The bulk of this early research phase is spent diving into the current offering. But it’s also the perfect time to do some competitor analysis—especially if we want some answers to the “what’s missing?” question.

It’s not all about missing features though. Execution is equally important. Our clients want to know how their users’ experience shapes up compared to the competition. And when it comes to user experience, performance is a huge factor. As Andy says, performance is a UX problem.

There’s no shortage of great tools out there for measuring (and monitoring) performance metrics, but they’re mostly aimed at developers. Quite rightly. Developers are the ones who can solve most performance issues. But that does make the tools somewhat impenetrable if you don’t speak the language of “time to first byte” and “first contentful paint”.

When we’re trying to show our clients the performance of their site—or their competitors—we need to tell a story.

Web Page Test is a terrific tool for measuring performance. It can also be used as a story-telling tool.

You can go to webpagetest.org/easy if you don’t need to tweak settings much beyond the typical site visit (slow 3G on mobile). Pop in your client’s URL and, when the test is done, you get a valuable but impenetrable waterfall chart. It’s not exactly the kind of thing I’d want to present to a client.

Fortunately there’s an attention-grabbing output from each test: video. Download the video of your client’s site loading. Then repeat the test with the URL of a competitor. Download that video too. Repeat for as many competitor URLs as you think appropriate.

Now take those videos and play them side by side. Presentation software like Keynote is perfect for showing multiple videos like this.

This is so much more effective than showing a table of numbers! Clients get to really feel the performance difference between their site and their competitors.

Running all those tests can take time though. But there are some other tools out there that can give a quick dose of performance information.

SpeedCurve recently unveiled Page Speed Benchmarks. You can compare the performance of sites within a particualar sector like travel, retail, or finance. By default, you’ll get a filmstrip view of all the sites loading side by side. Click through on each one and you can get the video too. It might take a little while to gather all those videos, but it’s quicker than using Web Page Test directly. And it might be that the filmstrip view is impactful enough for telling your performance story.

If, during your discovery phase, you find that performance is being badly affected by third-party scripts, you’ll need some way to communicate that. Request Map Generator is fantastic for telling that story in a striking visual way. Pop the URL in there and then take a screenshot of the resulting visualisation.

The beginning of a redesign project is also the time to take stock of current performance metrics so that you can compare the numbers after your redesign launches. Crux.run is really great for tracking performance over time. You won’t get any videos but you will get some very appealing charts and graphs.

Web Page Test, Page Speed Benchmarks, and Request Map Generator are great for telling the story of what’s happening with performance right nowCrux.run balances that with the story of performance over time.

Measuring performance is important. Communicating the story of performance is equally important.

Visitors, Developers, or Machines

Garrett’s observation is spot-on here:

I’ve been trying to understand the appeal of these frameworks by giving them an objective chance. I’ve expanded my knowledge of JavaScript and tried to give them the benefit of the doubt. They do have their places, but the only explanation I can come up with is that developers are taking a similar approach as Ruby and focusing on developer convenience and productivity. Only, instead of Ruby’s performance being tied to the CPU level, JavaScript frameworks push the performance burden to the client.

In both cases, the tradeoff happens in the name of developer happiness and productivity, but the strategies have entirely different consequences. With Ruby, the CPU is still (mostly) the responsibility of the development team, and it can be upgraded. With JavaScript, the page weight becomes an externality pushed onto visitors.

Friday, February 28th, 2020

Why 543 KB keep me up at night - Manuel Matuzović

How and when did I get to the point where I would consider a page weight of 4 MB on a large page and 500 KB on a small page normal?

This isn’t just a well-earned rant from Manuel. I mean, it *is that, but it’s also packed with practical performance advice.

Tuesday, February 25th, 2020

Reflections on software performance - Made of Bugs

I’ve really come to appreciate that performance isn’t just some property of a tool independent from its functionality or its feature set. Performance — in particular, being notably fast — is a feature in and of its own right, which fundamentally alters how a tool is used and perceived.

This is a fascinating look into how performance has knock-on effects beyond the obvious:

It’s probably fairly intuitive that users prefer faster software, and will have a better experience performing a given task if the tools are faster rather than slower.

What is perhaps less apparent is that having faster tools changes how users use a tool or perform a task.

This observation is particularly salient for web developers:

We have become accustomed to casually giving up factors of two or ten or more with our choices of tools and libraries, without asking if the benefits are worth it.

Monday, February 24th, 2020

Web bloat

Pages are often designed so that they’re hard or impossible to read if some dependency fails to load. On a slow connection, it’s quite common for at least one depedency to fail.

Fire up Reader Mode and read this excellent article informed by data from using a typically slow connection in rural USA today. Two findings are:

  1. A large fraction of the web is unusable on a bad connection. Even on a good (0% packetloss, no ping spike) dialup connection, some sites won’t load.
  2. Some sites will use a lot of data!

Saturday, February 15th, 2020

CrUX.RUN

This is so useful! Get instant results from Google’s Chrome User Experience Report without having to wait (or pay) for BigQuery.

Here’s an example of my site’s metrics over the last few months, complete with nice charts.

Friday, February 14th, 2020

Page Speed Benchmarks | SpeedCurve

This is going to be so useful for client work at Clearleft—instant snapshots of performance metrics across industries and regions!

For example, we’ve been working a lot with the travel sector, and now we can call up these benchmarks without having to generate a whole bunch of Web Page Test results ourselves.

See Tammy’s blog post for me details.

Thursday, February 6th, 2020

Innovation Can’t Keep the Web Fast | CSS-Tricks

I’ve come to accept that our current approach to remedy poor performance largely consists of engineering techniques that stem from the ill effects of our business, product management, and engineering practices. We’re good at applying tourniquets, but not so good at sewing up deep wounds.

It’s becoming increasingly clear that web performance isn’t solely an engineering problem, but a problem of people.

Hydration

As you may have noticed, I’m a fan of progressive enhancement.

It’s not cool. It’s often at odds with “modern” web development, so I end up looking like an old man yelling at a cloud to get off my lawn. Or something.

At its heart though, progressive enhancement seems fairly uncontroversial and inoffensive to me. It’s an approach. A mindset. Here’s how I describe it in Resilient Web Design:

  1. Identify core functionality.
  2. Make that functionality available using the simplest possible technology.
  3. Enhance!

Progressive enhancement makes use of the principle of least power:

Choose the least powerful language suitable for a given purpose.

That’s step two of the three-step process. But the third step is vital.

I think a lot of the hostility towards progressive enhancement comes from a misunderstanding of that three-step process, perhaps thinking that it stops at step two. I’m sure that some have intrepreted progressive enhancement as preventing developers from using the latest and greatest technology. Nothing could be further from the truth!

Taking a layered approach to building on the web gives you permission to try cutting‐edge JavaScript APIs, regardless of how many or how few browsers currently implement them.

The most common misunderstanding of progressive enhancement is that it’s inherently about JavaScript. That’s not true. You can apply progressive enhancement at every step of front-end development: HTML, CSS, and JavaScript.

But because of JavaScript’s strict error-handling model (at least compared to HTML and CSS), it’s in the JavaScript layer that the lack of a progressive enhancement mindset is most often felt.

That’s why I was saddened by the rise of frameworks and mindsets that assume the availability of JavaScript. Single page apps generally follow this assumption. Everything is delivered via JavaScript: content, markup, styles, and behaviour.

This leads to a terrible situation for performance. The user is left staring at a blank screen, waiting for something—anything!—to appear. Browsers are optimised to stream HTML as soon as they can. Delivering your content via JavaScript rather than HTML means you’re not taking advantage of that optimisation. Your users suffer.

But I was very heartened when I saw the pendulum start to swing back the other way a bit…

Let’s say you’re using a JavaScript framework like React. But the reason you’re using it isn’t because you’re doing anything particularly complex in the browser involving state management. You might be using React because you really like the way it encourages modularity and componentisation.

A few years ago, making a single page app was pretty much the only way you could use React. For you as a developer to experience the benefits of modularity and componentisation, users had to pay the price in the payload (and fragility) of client-side JavaScript.

That’s no longer the case. Now that we can run JavaScript on the server, it’s possible to build in a modular, componentised way and still use progressive enhancement.

When I first heard about Gatsby and Next.js, I thought that was the selling point. Run React on the server; send pre-generated HTML down the wire to the user; then enhance with client-side JavaScript.

But that’s not exactly how it works. The pre-generated HTML isn’t functional. It still needs a bucketload of JavaScript before it can do anything. The actual process is: Run React on the server; send pre-generated HTML down the wire to the user; then send everything again but this time in JavaScript, bundled with the entire React library.

This leads to a situation for users that’s almost worse than before. Instead of staring at a blank screen, now they get HTML lickety-split—excellent! But if they try to interact with what’s on screen, they’ll find that nothing is working yet. Even worse, once the JavaScript is delivered, and is being parsed, they probably can’t even scroll—their device is too busy interpreting all that JavaScript. Your users suffer.

All your content is sent twice. First HTML is sent from the server. These days this is called “server-side rendering”, even though for decades the technical term was “serving a web page” (I’m pretty sure the rendering part happens in a browser). Then a JavaScript library—plus all your bespoke JavaScript—is loaded. Then all your content is loaded again as JSON.

So you’ve got a facade of an interface that you can’t actually interact with until a deluge of JavaScript has been loaded, parsed and executed. The term used for this stage of the process is “hydration”, which makes it sound more like a relaxing treatment from Gwyneth Paltrow than the horrible user experience it is.

The idea is that subsequent navigations—which will happen with Ajax—should be snappy. But the price has already been paid by then. The initial loading experience is jagged and frustrating.

Don’t get me wrong: server-side rendering is great …if what you’re sending from the server is functional. It’s the combination of hollow HTML sent from the server, followed by a huge browser-freezing dump of JavaScript that is an anti-pattern.

This use of server-side rendering followed by hydration feels like progressive enhancement, because it separates out the delivery of markup and scripts. But it’s missing the mindset.

The layered approach of progressive enhancement echoes the separation of concerns in the front-end stack: HTML, CSS, and JavaScript—each layer expressing more power. But while these concepts are related, they’re not interchangable. Separating out the layers of your tech stack isn’t necessarily progressive enhancement. If you have some HTML that relies on JavaScript to be useful, then there’s no benefit in separating that HTML into a separate payload. The HTML that you initially send down the wire needs to be functional (at least at a basic level) before the JavaScript arrives.

I was a little disappointed to see Kyle Simpson—who I admire greatly—conflate separation of concerns with progressive enhancement in his talk from JSCamp 2019:

This content is here. I can see it, and it’s even styled. But I can’t click on the damn button because nothing has loaded in the JavaScript layer yet.

Anybody experienced that where you’ve been on a web page and it’s not really fully functional yet? I can see something but I can’t actually make any usage of it yet.

These are all things that cropped out of our thought process that said: “Let’s build the web in layers. Let’s deliver it progressively in layers. Because that’s morally right. We call this progressive enhancement. And let’s not worry too much about all these potential user experience flaws that may happen.”

That’s a spot-on description of server-side rendering and hydration, but it’s a gross mischaracterisation of progressive enhancement.

That button that requires JavaScript to work? That should’ve been generated with JavaScript. (For example, if you’re building a complex web app, consider sending a read-only view down the wire in HTML—then add any interactive interface elements with JavaScript in the browser.)

If people are equating progressive enhancement with thoughtless server-side rendering and hydration, then I can see why they’d be hostile towards it.

Users would be better served with unprogressive non-enhancement:

You take some structured content, which follows the vertical flow of the document in a way that everyone understands.

Which people traverse easily by either dragging their scroll bar with their mouse, or operating the keyboard using the up and down keys, or using the spacebar.

Or if they’re using a touch device, simply flicking backwards and forwards in that easy way that we’ve all become used to. What you do is you take that, and you fucking well leave it alone.

Alas, that’s not what tools like Gatsby offer. The latest post on their blog is called Why Gatsby is better with JavaScript:

But what about sites or pages where there is no client-side interactivity? Even for those pages, Gatsby offers performance benefits by including JavaScript.

I beg to differ.

(By the way, that same blog post also initially tried to equate the performance hit of client-side JavaScript with the performance hit of images. Andy explains why that’s disingenuous.)

Hope is on the horizon for React in the form of partial hydration. I sincerely hope that it will become the default way of balancing server-side rendering with just-in-time client-side interaction.

The situation we have now is the worst of both worlds: server-side rendering followed by a tsunami of hydration. It has a whiff of progressive enhancement to it (because there’s a cosmetic separation of concerns) but it has none of the user benefits.

Monday, February 3rd, 2020

Google Maps Hacks, Performance and Installation, 2020 By Simon Weckert

I can’t decide if this is industrial sabotage or political protest. Either way, I like it.

99 second hand smartphones are transported in a handcart to generate virtual traffic jam in Google Maps.Through this activity, it is possible to turn a green street red which has an impact in the physical world by navigating cars on another route to avoid being stuck in traffic

Thursday, January 23rd, 2020

Lightning-Fast Web Performance: an online lecture series from Scott Jehl

You know that this online course from Scott is going to be excellent—get in there!