53% of mobile visits leave a page that takes longer than 3 seconds to load. That means that a large number of visitors probably abandoned these sites because they were staring at a blank screen for 3 seconds, said “fuck it,” and left approximately half way before the page showed up. The fact that the next page interaction would have been quicker—assuming all the JS files even downloaded correctly in the first attempt—doesn’t amount to much if they didn’t stick around for the first page to load. What was gained by putting the business logic in the front end in this scenario?
Monday, March 25th, 2019
Friday, March 22nd, 2019
I think I physically winced on more than one occassion as I read through Jake’s report here.
He makes an interesting observation at the end:
However, none of the teams used any of the big modern frameworks. They’re mostly Wordpress & Drupal, with a lot of jQuery. It makes me feel like I’ve been in a bubble in terms of the technologies that make up the bulk of the web.
Yes! This! Contrary to what you might think reading through the latest and greatest tips and tricks from the front-end community, the vast majority of sites out there on the web are not being built with React, Vue, webpack or any other “modern” tools.
Two of my favourite things: indie web and service workers.
This makes me so happy. I remember saying when my book came out, that the best feedback I could possibly get would be readers making their websites work offline. The same can be said for the talk of the book.
A fascinating look at the web today with IE8. And it’s worth remembering who might be experiencing the web like this:
Whoever they are, you can bet they’re not using an old browser just to annoy you. Nobody deliberately chooses a worse browsing experience.
The article also outlines two possible coping strategies:
- Polyfilling Strive for feature parity for all by filling in the missing browser functionality.
- Progressive Enhancement Start from a core experience, then use feature detection to layer on functionality.
Take a wild guess as to which strategy I support.
There’s a bigger point made at the end of all this:
IE8 is today’s scapegoat. Tomorrow it’ll be IE9, next year it’ll be Safari, a year later it might be Chrome. You can swap IE8 out for ‘old browser of choice’. The point is, there will always be some divide between what browsers developers build for, and what browsers people are using. We should stop scoffing at that and start investing in robust, inclusive engineering solutions. The side effects of these strategies tend to pay dividends in terms of accessibility, performance and network resilience, so there’s a bigger picture at play here.
Monday, March 18th, 2019
A good talk from from Chris Ferdinandi, who says:
Wednesday, March 13th, 2019
This looks like it could be an interesting library of interface patterns.
Thursday, March 7th, 2019
Going Offline—the talk of the book
I gave a new talk at An Event Apart in Seattle yesterday morning. The talk was called Going Offline, which the eagle-eyed amongst you will recognise as the title of my most recent book, all about service workers.
I was quite nervous about this talk. It’s very different from my usual fare. Usually I have some big sweeping arc of history, and lots of pretentious ideas joined together into some kind of narrative arc. But this talk needed to be more straightforward and practical. I wasn’t sure how well I would manage that brief.
I knew from pretty early on that I was going to show—and explain—some code examples. Those were the parts I sweated over the most. I knew I’d be presenting to a mixed audience of designers, developers, and other web professionals. I couldn’t assume too much existing knowledge. At the same time, I didn’t want to teach anyone to such eggs.
In the end, there was an overarching meta-theme to talk, which was this: logic is more important than code. In other words, figuring out what you’re trying to accomplish (and describing it clearly) is more important than typing curly braces and semi-colons. Programming is an act of translation. Before you can translate something, you need to be able to articulate it clearly in your own language first. By emphasising that point, I hoped to make the code less overwhelming to people unfamilar with it.
I had tested the talk with some of my Clearleft colleagues, and they gave me great feedback. But I never know until I’ve actually given a talk in front of a real conference audience whether the talk is any good or not. Now that I’ve given the talk, and received more feedback, I think I can confidentally say that it’s pretty damn good.
My goal was to explain some fairly gnarly concepts—let’s face it: service workers are downright weird, and not the easiest thing to get your head around—and to leave the audience with two feelings:
- This is exciting, and
- This is something I can do today.
I deliberately left time for questions, bribing people with free copies of my book. I got some great questions, and I may incorporate some of them into future versions of this talk (conference organisers, if this sounds like the kind of talk you’d like at your event, please get in touch). Some of the points brought up in the questions were:
- Is there some kind of wizard for creating a typical service worker script for any site? I didn’t have a direct answer to this, but I have attempted to make a minimal viable service worker that could be used for just about any site. Mostly I encouraged the questioner to roll their sleeves up and try writing a bespoke script. I also mentioned the Workbox library, but I gave my opinion that if you’re going to spend the time to learn the library, you may as well spend the time to learn the underlying language.
- What are some state-of-the-art progressive web apps for offline user experiences? Ooh, this one kind of stumped me. I mean, the obvious poster children for progressive webs apps are things like Twitter, Instagram, and Pinterest. They’re all great but the offline experience is somewhat limited. To be honest, I think there’s more potential for great offline experiences by publishers. I especially love the pattern on personal sites like Una’s and Sara’s where people can choose to save articles offline to read later—like a bespoke Instapaper or Pocket. I’d love so see that pattern adopted by some big publications. I particularly like that gives so much more control directly to the end user. Instead of trying to guess what kind of offline experience they want, we give them the tools to craft their own.
- Do caches get cleaned up automatically? Great question! And the answer is mostly no—although browsers do have their own heuristics about how much space you get to play with. There’s a whole chapter in my book about being a good citizen and cleaning up your caches, but I didn’t include that in the talk because it isn’t exactly exciting: “Hey everyone! Now we’re going to do some housekeeping—yay!”
- What kind of things are in the future for service workers? Excellent question! If you think about it, a service worker is kind of a conduit that gives you access to different APIs: the Cache API and the Fetch API being the main ones now. A service worker is like an airport and the APIs are like the airlines. There are other APIs that you can access through service workers. Notifications are available now on desktop and on Android, and they’ll be coming to iOS soon. Background Sync is another powerful API accessed through service workers that will get more and more browser support over time. The great thing is that you can start using these APIs today even if they aren’t universally supported. Then, over time, more and more of your users will benefit from those enhancements.
If you attended the talk and want to learn more about about service workers, there’s my book (obvs), but I’ve also written lots of blog posts about service workers and I’ve linked to lots of resources too.
Finally, here’s a list of links to all the books, sites, and articles I referenced in my talk…
- Resilient Web Design
- The Prime Number Shitting Bear
- The Session
- Una Kravets
- Sara Soueidan
- dConstruct Archive
Progressive Web Apps
- What the heck is a “Progressive Web App”? Seriously. by Ben Halpern
- Building Progressive Web Apps by Diogo Cunha
- Before You Build a PWA You Need a SPA by Mark Muskardin
- Tweet by Jake Archibald
- What is a PWA by Salva de la Puente
- Naming Progressive Web Apps by Frances Berriman
- Progressive Web App Checklist by Google
Wednesday, March 6th, 2019
Are many of the modern frontend tools and practices just technical debt in disguise?
Ooh, good question!
Tuesday, March 5th, 2019
Hui-Jing talks through her process of building a to-do app on Glitch using a progressive enhancement mindset:
Move Fast and Don’t Break Things by Scott Jehl
Scott Jehl is speaking at An Event Apart in Seattle—yay! His talk is called Move Fast and Don’t Break Things:
Performance is a high priority for any site of scale today, but it can be easier to make a site fast than to keep it that way. As a site’s features and design evolves, its performance is often threatened for a number of reasons, making it hard to ensure fast, resilient access to services. In this session, Scott will draw from real-world examples where business goals and other priorities have conflicted with page performance, and share some strategies and practices that have helped major sites overcome those challenges to defend their speed without compromises.
The title is a riff on the “move fast and break things” motto, which comes from a more naive time on the web. But Scott finds part of it relatable. Things break. We want to move fast without breaking things.
This is a performance talk, which is another kind of moving fast. Scott starts with a brief history of not breaking websites. He’s been chipping away at websites for 20 years now. Remember Positioning Is Everything? How about Quirksmode
In the early days, building a website that was "not broken" was difficult, but it was difficult for different reasons. We were focused on consistency. We had deal with differences between browsers. There were two ways of dealing with browsers: browser detection and feature detection.
The feature-based approach was more sustainable but harder. It fits nicely with the practice of progressive enhancement. It's a good mindset for dealing with the explosion of devices that kicked off later. Touch screens made us rethink our mouse and hover-centric matters. That made us realise how much keyboard-driven access mattered all along.
Browsers exploded too. And our data networks changed. With this explosion of considerations, it was clear that our early ideas of “not broken” didn’t work. Our notion of what constituted “not broken” was itself broken. Consistency just doesn’t cut it.
But there was a comforting part to this too. It turned out that progressive enhancement was there to help …even though we didn’t know what new devices were going to appear. This is a recurring theme throughout Scott’s career. So given all these benefits of progressive enhancement, it shouldn’t be surprising that it turns out to be really good for performance too. If you practice progressive enhancement, you’re kind of a performance expert already.
People started talking about new performance metrics that we should care about. We’ve got new tools, like Page Speed Insights. It gives tangible advice on how to test things. Web Page Test is another great tool. Once you prove you’re a human, Web Page Test will give you loads of details on how a page loaded. And you get this great visual timeline.
This is where we can start to discuss the metrics we want to focus on. Traditionally, we focused on file size, which still matters. But for goal-setting, we want to focus on user-perceived metrics.
The average time for this on the web right now is around six seconds. That’s broken. The render blockers are the problem here.
Consider assets like scripts. Can you get the browser to load them without holding up the rendering of the page? If you can add
defer to a
script element in the
head, you should do that. Sometimes that’s not an option though.
For CSS, it’s tricky. We’ve delivered the HTML that we need but we’ve got to wait for the CSS before rendering it. So what can you bundle into that initial payload?
You can user server push. This is a new technology that comes with HTTP2. H2, as it’s called, is very performance-focused. Just turning on H2 will probably make your site faster. Server push allows the server to send files to the browser before the browser has even asked for them. You can do this with directives in Apache, for example. You could push CSS whenever an HTML file is requested. But we need to be careful not to go too far. You don’t want to send too much.
Server push is great in moderation. But it is new, and it may not even be supported by your server.
Another option is to inline CSS (well, actually Scott, this is technically embedding CSS). It’s great for first render, but isn’t it wasteful for caching? Scott has a clever pattern that uses the Cache API to grab the contents of the inlined CSS and put a copy of its contents into the cache. Then it’s ready to be served up by a service worker.
By the way, this isn’t just for CSS. You could grab the contents of inlined SVGs and create cached versions for later use.
So inlining CSS is good, but again, in moderation. You don’t want to embed anything bigger than 15 or 20 kilobytes. You might want separate out the critical CSS and only embed that on first render. You don’t need to go through your CSS by hand to figure out what’s critical—there are tools that to do this that integrate with your build process. Embed that critical CSS into the
head of your document, and also start preloading the full CSS. Here’s a clever technique that turns a preload link into a stylesheet link:
<link rel="preload" href="site.css" as="style" onload="this.rel='stylesheet'">
Also include this:
<noscript><link rel="stylesheet" href="site.css"></noscript>
You can also optimise for return visits. It’s all about the cache.
In the past, we might’ve used a cookie to distinguish a returning visitor from a first-time visitor. But cookies kind of suck. Here’s something that Scott has been thinking about: service workers can intercept outgoing requests. A service worker could send a header that matches the current build of CSS. On the server, we can check for this header. If it’s not the latest CSS, we can server push the latest version, or inline it.
The neat thing about service workers is that they have to install before they take over. Scott makes use of this install event to put your important assets into a cache. Only once that is done to we start adding that extra header to requests.
Watch out for an article on the Filament Group blog on this technique!
With performance, more weight doesn’t have to mean more wait. You can have a heavy page that still appears to load quickly by altering the prioritisation of what loads first.
Web pages are very heavy now. There’s a real cost to every byte. Tim’s WhatDoesMySiteCost.com shows that the CNN home page costs almost fifty cents to load for someone in America!
Scott believes easier to make a fast website than to keep a fast website. And that’s down to all the third-party scripts that people throw in: analytics, ads, tracking. They can wreak havoc on all your hard work.
These scripts apparently contribute to the business model, so it can be hard for us to make the case for removing them. Tools like SpeedCurve can help people stay informed on the impact of these scripts. It allows you to set up performance budgets and it shows you when pages go over budget. When that happens, we have leverage to step in and push back.
Assuming you lose that battle, what else can we do?
These days, lots of A/B testing and personalisation happens on the client side. The tooling is easy to use. But they are costly!
A typical problematic pattern is this: the server sends one version of the page, and once the page is loaded, the whole page gets replaced with a different layout targeted at the user. This leads to a terrifying new metric that Scott calls Second Meaningful Content.
Assuming we can’t remove the madness, what can we do? We could at least not do this for first-time visits. We could load the scripts asyncronously. We can preload the scripts at the top of the page. But ideally we want to move these things to the server. Server-side A/B testing and personalisation have existed for a while now.
Scott has been experimenting with a middleware solution. There’s this idea of server workers that Cloudflare is offering. You can manipulate the page that gets sent from the server to the browser—all the things you would do for an A/B test. Scott is doing this by using comments in the HTML to demarcate which portions of the page should be filtered for testing. The server worker then deletes a block for some users, and deletes a different block for other users. Scott has written about this approach.
The point here isn’t about using Cloudflare. The broader point is that it’s much faster to do these things on the server. We need to defend our user’s time.
Another issue, other than third-party scripts, is the page weight on home pages and landing pages. Marketing teams love to fill these things with enticing rich imagery and carousels. They’re really difficult to keep performant because they change all the time. Sometimes we’re not even in control of the source code of these pages.
We can advocate for new best practices like responsive images. The
srcset attribute on the
img element; the
picture element for when you need more control. These are great tools. What’s not so great is writing the markup. It’s confusing! Ideally we’d have a CMS drive this, but a lot of the time, landing pages fall outside of the purview of the CMS.
Scott has been using Vue.js to make a responsive image builder—a form that people can paste their URLs into, which spits out the markup to use. Anything we can do by creating tools like these really helps to defend the performance of a site.
Another thing we can do is lazy loading. Focus on the assets. The BBC homepage uses some lazy loading for images—they blink into view as your scroll down the page. They use LazySizes, which you can find on Github. You use
data- attributes to list your image sources. Scott realises that LazySizes is not progressive enhancement. He wouldn’t recommend using it on all images, just some images further down the page.
But thankfully, we won’t need these workarounds soon. Soon we’ll have lazy loading in browsers. There’s a
lazyload attribute that we’ll be able to set on
<img src=".." alt="..." lazyload="on">
It’s not implemented yet, but it’s coming in Chrome. It might be that this behaviour even becomes the default way of loading images in browsers.
If you dig under the hood of the implementation coming in Chrome, it actually loads all the images, but the ones being lazyloaded are only sent partially with a 206 response header. That gives enough information for the browser to lay out the page without loading the whole image initially.
To wrap up, Scott takes comfort from the fact that there are resilient patterns out there to help us. And remember, it is our job to defend the user’s experience.
How to Think Like a Front-End Developer by Chris Coyier
Alright! It’s day two of An Event Apart in Seattle. The first speaker of the day is Chris Coyier. His talk is called How to Think Like a Front-End Developer. From the website:
The job title “front-end developer” is very real: job boards around the world confirm that. But what is that job, exactly? What do you need to know to do it? You might think those answers are pretty cut and dried, but they’re anything but; front-end development is going through something of an identity crisis. In this engaging talk, Chris will explore this identity through the lens of someone who has self-identified as a front-end developer for a few decades, but more interestingly, through many conversations he’s had with other successful front-end developers. You’ll see just how differently this job can be done and how differently people and companies can think of this role—not just for the sake of doing so, but because you’ll learn to be better at your own jobs by understanding how other people are good at theirs.
I’m going to see if I can keep up with Chris’s frenetic pace…
Chris has his own thoughts about what front-end dev is but he wants to share other ideas too. First of all, some grammar:
I work as a front-end developer.
I work on the front end.
Those are correct. These are not:
I work as a front end developer.
I work on the front-end.
And this is just not a word:
Lots of people are hiring front-end developers. So it’s definitely a job and a common job title. But what does it mean. Chris and Dave talked to eight different people on their Shop Talk Show podcast. Some highlights:
Eric feels that the term “front-end developer” is newer than the CSS Zen Garden. Everyone was a webmaster, or as we’d say now, a full-stack developer. But if someone back then used the term “front-end developer”, he’d know what it meant.
Mina says it deals with things you can see. If it’s a user-facing interface, that’s front-end development.
Trent says that he thinks of himself as a web designer and web builder. He doesn’t feel he has the deep expertise of a developer, and yet he spends all of his time in the browser.
So our job is in the browser. You deal with the browser (moreso than other roles). And by the way, there are a lot of browsers out there.
Maybe the user is what differentiates front-end work. Monica says that a back-end developer is allowed not to care about the user if their job is putting a database together. It’s totally fine not to call yourself a front-end developer, but if you do, you need to care about the user.
There are tons of different devices and browsers. It’s overwhelming. So we just gave up.
So, a front-end developer:
- Is a job and a job title.
- It deals with browsers, devices, and users.
- But what skills does it involve?
It’s taken for granted that you can use a computer. There’s also the soft skills of interacting with co-workers. Then there are the language-specific core skills. Finally, there are the bonus skills—all the stuff that makes you you.
The languages you need to strongly understand to read, write and maintain them.
Peggy believes that as a front-end developer you need to have a basic proficiency in accessibility too. This is, after all, about user-facing interfaces.
The Figma team have a somewhat over-engineered graphic of all the skillsets that people might have, between “baseline” and “supplementary”.
Perhaps we all share a common trunk of skills, and then we branch in different directions.
You could imagine two people called front-end developers meeting, and having nothing in common to talk about. Maybe sports.
Brad says he doesn’t want to be configuring build tools. He thinks of himself as being at the front of front-end development, whereas other people are at the back of front-end development.
This divide is super frustrating to people right now.
Let’s look at CodePen. There’s a little heart icon on each pen. It’s an icon component. And the combination of the heart and the overall count is also a component. And the bar of items altogether—that’s also a component. And the pen it sits under is a component. And the page it’s in is a component. And the URL for that page is a component. Now the whole site is a front-end developer’s concern.
In the past, a front-end developer would ask a back-end developer for an API endpoint. Now with GraphQL, the front-end developer can craft a query to get exactly what they need. Sure, the GraphQL stuff had to be set up in the first place, but that’s one-time task. Once it’s set up, the front-end developer has everything they need.
All the old work hasn’t gone away either. Semantics, accessibility, styling—that’s still the work of a front-end developer as well as all of the new stuff listed above.
Hiring is a big part of this. Lara Schenk talks about going for an interview where she met 90% of the skills listed. Then in an interview, she was asked to do a fizzbuzz test. That’s not the way that Lara thinks. She would’ve been great for that job, but this single task derailed her. She wrote about it, and got snarky comments from people who thought she should’ve been able to do the task. But Lara’s main point was the mismatch between what was advertised and what was actually being hired for.
You see a job posting for front-end developer. Who is that for? Is it for someone into React, webpack, and GraphQL? Or is it for someone into SVG, interaction design, and accessibility? They’re both front-end developers. And remember, they can learn one another’s skills, but when it comes to hiring, it has to be about the skills people have right now.
Peggy talks about how specialised your work can be. You can specialise in SVG. You can specialise in APIs and data.
We’re probably not going to solve this right now. The hiring part is definitely the worst part right now. One solution is to use plain language in job posts. Make it clear what you’re looking for right now and explain what background you’re coming from. Use words instead of a laundry list of requirements.
Heydon Pickering talks about full-stack developers. Their core skills are hardcore computer science skills.
Brad Frost concurs. It tends not to be the other way around. The output tends to be the badly-sketched front of the horse.
Even if there is a divide, that doesn’t absolve any of us from doing a good job. That’s true whether it’s computer science tasks or markup and CSS.
Despite the divide, performance, accessibility, and user experience are all our jobs.
Maybe this term “front-end developer” needs rethinking.
The brain game
Let’s peak into the minds of very different front-end developers. Chris and Dave went to Dribbble, pulled up a bunch of designs and put them in front of their guests on the Shop Talk Show.
Here’s a design of a page.
- Brad looks at the design and sees a lot of components of different sizes and complexity.
- Mina sees a bunch of media objects.
- Eric sees HTML structures. That’s a heading. That’s a list. Over there is an unordered list.
- Sam sees a lot of typography. She sees a type system.
- Trent immediately starts thinking about how the design is supposed to work in different screen sizes.
Here’s a different, more image-heavy design.
- Mina would love to tackle the animations.
- Trent sees interesting textures and noise. He wonders how he could achieve those effects without exporting giant image files.
- Brad, unsurprisingly, sees components, even in a seemingly bespoke layout.
- Eric immediately sees a lot of SVG.
- Sam needs to know what the HTML is.
Here’s a more geometric design.
- Sam is drawn to the typography.
- Mina sees an opportunity to use writing modes.
- Trent sees a design that would reflow and reshape itself well.
- Eric sees something with writing mode, grid, and custom fonts.
Here’s a financial mobile UI.
- Trent wants to run it through a colour-contrast analyser, and he wants to know if the font size is too small.
Here’s a crazy festival website.
- Mina wonders if it needs a background video, but worries about the performance.
Here’s an on-trend mobile design.
- Monica sees something that looks like every other website.
- Ben wonders whether it will work in other parts of the world. How will the interactions work? Separate pages or transitions? How will it feel?
Here’s an image-heavy design.
- Monica wonders about the priority of which images to load first.
Here’s an extreme navigation with big images.
- Ben worries about the performance on slow connections.
- Monica gets stressed out about how much happens when you just click on a link.
- Peggy sees something static and imagines using Gatsby for it.
Here’s a design that’s map-based.
- Ben worries about the size of the touch targets.
- Monica sees an opportunity to use SVGs.
Here’s a card UI.
- Ben wonders what the browser support is. Can we use CSS grid or do we have to use something older?
- Monica worries that this needs drag’n’drop. Now you’ve got a nightmare scenario.
Chris has been thinking about and writing about this topic of what makes someone a front-end developer, and what makes someone a good front-end developer. The debate will continue…
Wednesday, February 27th, 2019
This aspect of Vue appeals to me more than the all-or-nothing vibe I get from React:
By enabling incremental adoption, Vue’s progressive nature means that individuals can start using it here and there, a bit at a time, without having to do massive rewrites.
Tuesday, February 26th, 2019
There’s a lot here that ties in with what I was talking about at New Adventures around the rule of least power in technology choice.
I’m not sure if I agree with describing CSS as being state-based. The example that illustrates this—a
:hover style—feels like an exception rather than a typical example of CSS.
Monday, February 25th, 2019
Accessibility on The Session
These forms have been enhanced with some Ajax to add some motion design: instead of refreshing the whole page, the next form is grabbed from the server while the previous one swooshes off the screen.
You can see similar functionality—without the animation—wherever there’s pagination on the site.
The pagination is using Ajax to enhance regular prev/next links—here’s the code.
The multi-step forms are using Ajax to enhance regular form submissions—here’s the code for that.
Both of those are using a wrapper I wrote for XMLHttpRequest.
That wrapper also adds some ARIA attributes. The region of the page that will be updated gets an
aria-live value of
polite. Then, whenever new content is being injected, the same region gets an
aria-busy value of
true. Once the update is done, the
aria-busy value gets changed back to
That all seems to work fine, but I was also giving the same region of the page an
aria-atomic value of
true. My thinking was that, because the whole region was going to be updated with new content from the server, it was safe to treat it as one self-contained unit. But it looks like this is what was causing the problem, especially when I was also adding and removing
class values on the region in order to trigger animations. VoiceOver seemed to be getting a bit confused and overly verbose.
I’ve removed the
aria-atomic attribute now. True to its name, I’m guessing it’s better suited to small areas of a document rather than big chunks. (If anyone has a good primer on when to use and when to avoid
aria-atomic, I’m all ears).
I was glad I was able to find a fix—hopefully one that doesn’t negatively impact the experience in other screen readers. As is so often the case, the issue was with me trying to be too clever with ARIA, and the solution was to ease up on adding so many ARIA attributes.
For me, all of this really highlights the beauty of the web, when everyone is able to contribute to a community like The Session, regardless of what kind of software they may be using. In the tunes section, that’s really helped by the use of ABC notation, as I wrote five years ago:
One of those screen-reader users got in touch with me shortly after joining to ask me to explain what ABC was all about. I pointed them at some explanatory links. Once the format “clicked” with them, they got quite enthused. They pointed out that if the sheet music were only available as an image, it would mean very little to them. But by providing the ABC notation alongside the sheet music, they could read the music note-for-note.
That’s when it struck me that ABC notation is effectively alt text for sheet music!
Then, for those of use who can read sheet music, the text of the ABC notation is automatically turned into an SVG image using the brilliant abcjs. It’s like an enhancement that’s applied, I dunno, what’s the word …progressively.
Saturday, February 23rd, 2019
Thursday, February 21st, 2019
A tiny lesson in query selection
We have a saying at Clearleft:
Everything is a tiny lesson.
I bet you learn something new every day, even if it’s something small. These small tips and techniques can easily get lost. They seem almost not worth sharing. But it’s the small stuff that takes the least effort to share, and often provides the most reward for someone else out there. Take for example, this great tip for getting assets out of Sketch that Cassie shared with me.
querySelector to get a reference to an element in the DOM:
var someElement = document.querySelector('.someClass');
Before going any further, check to make sure that the reference isn’t falsey (in other words, make sure that DOM node actually exists):
if (!someElement) return;
That will exit the script if there’s no element with a class of
someClass on the page.
The situation that tripped us up was like this:
var myLinks = document.querySelectorAll('a.someClass'); if (!myLinks) return;
That should exit the script if there are no
A elements with a class of
As it turns out,
querySelectorAll is subtly different to
querySelector. If you give
querySelector a reference to non-existent element, it will return a value of
null (I think). But
querySelectorAll always returns an array (well, technically it’s a NodeList but same difference mostly). So if the selector you pass to
querySelectorAll doesn’t match anything, it still returns an array, but the array is empty. That means instead of just testing for its existence, you need to test that it’s not empty by checking its
if (!myLinks.length) return;
That’s a tiny lesson.
Wednesday, February 20th, 2019
If you really, really have to add Google Analytics to a sites, here’s a way to do it in a more performant way, without the odious Google Tag Manager.
Tuesday, February 19th, 2019
If there are no specific reasons to build a single-page application, I will go with a traditional server-rendered architecture every day of the week.