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Saturday, August 1st, 2020

this vs that - What is the difference between ___ and ___ in the front-end development?

A handy reference for explaining the differences between confusingly similar bits of HTML, CSS, and JavaScript.

Friday, July 24th, 2020

Custom Property Coverup | Amber’s Website

This is a great bit of detective work by Amber! It’s the puzzling case of The Browser Dev Tools and the Missing Computed Values from Custom Properties.

Who do I know working on dev tools for Chrome, Firefox, or Safari that can help Amber find an answer to this mystery?

Tuesday, July 7th, 2020

Custom properties

I made the website for the Clearleft podcast last week. The design is mostly lifted straight from the rest of the Clearleft website. The main difference is the masthead. If the browser window is wide enough, there’s a background image on the right hand side.

I mostly added that because I felt like the design was a bit imbalanced without something there. On the home page, it’s a picture of me. Kind of cheesy. But the image can be swapped out. On other pages, there are different photos. All it takes is a different class name on that masthead.

I thought about having the image be completely random (and I still might end up doing this). I’d need to use a bit of JavaScript to choose a class name at random from a list of possible values. Something like this:

var names = ['jeremy','katie','rich','helen','trys','chris'];
var name = names[Math.floor(Math.random() * names.length)];
document.querySelector('.masthead').classList.add(name);

(You could paste that into the dev tools console to see it in action on the podcast site.)

Then I read something completely unrelated. Cassie wrote a fantastic article on her site called Making lil’ me - part 1. In it, she describes how she made the mouse-triggered animation of her avatar in the footer of her home page.

It’s such a well-written technical article. She explains the logic of what she’s doing, and translates that logic into code. Then, after walking you through the native code, she shows how you could use the Greeksock library to achieve the same effect. That’s the way to do it! Instead of saying, “Here’s a library that will save you time—don’t worry about how it works!”, she’s saying “Here’s it works without a library; here’s how it works with a library; now you can make an informed choice about what to use.” It’s a very empowering approach.

Anyway, in the article, Cassie demonstrates how you can use custom properties as a bridge between JavaScript and CSS. JavaScript reads the mouse position and updates some custom properties accordingly. Those same custom properties are used in CSS for positioning. Voila! Now you’ve got the position of an element responding to mouse movements.

That’s what made me think of the code snippet I wrote above to update a class name from JavaScript. I automatically thought of updating a class name because, frankly, that’s how I’ve always done it. I’d say about 90% of the DOM scripting I’ve ever done involves toggling the presence of class values: accordions, fly-out menus, tool-tips, and other progressive disclosure patterns.

That’s fine. But really, I should try to avoid touching the DOM at all. It can have performance implications, possibly triggering unnecessary repaints and reflows.

Now with custom properties, there’s a direct line of communication between JavaScript and CSS. No need to use the HTML as a courier.

This made me realise that I need to be aware of automatically reaching for a solution just because that’s the way I’ve done something in the past. I should step back and think about the more efficient solutions that are possible now.

It also made me realise that “CSS variables” is a very limiting way of thinking about custom properties. The fact that they can be updated in real time—in CSS or JavaScript—makes them much more powerful than, say, Sass variables (which are more like constants).

But I too have been guilty of underselling them. I almost always refer to them as “CSS custom properties” …but a lot of their potential comes from the fact that they’re not confined to CSS. From now on, I’m going to try calling them custom properties, without any qualification.

Friday, July 3rd, 2020

Uncommon CSS Properties

I count at least three clever CSS techniques I didn’t know about.

Saturday, June 13th, 2020

CSS Custom Properties Fail Without Fallback · Matthias Ott – User Experience Designer

Matthias has a good solution for dealing with the behaviour of CSS custom properties I wrote about: first set your custom properties with the fallback and then use feature queries (@supports) to override those values.

Thursday, June 11th, 2020

CSS custom properties and the cascade

When I wrote about programming CSS to perform Sass colour functions I said this about the brilliant Lea Verou:

As so often happens when I’m reading something written by Lea—or seeing her give a talk—light bulbs started popping over my head (my usual response to Lea’s knowledge bombs is either “I didn’t know you could do that!” or “I never thought of doing that!”).

Well, it happened again. This time I was reading her post about hybrid positioning with CSS variables and max() . But the main topic of the post wasn’t the part that made go “Huh! I never knew that!”. Towards the end of her article she explained something about the way that browsers evaluate CSS custom properties:

The browser doesn’t know if your property value is valid until the variable is resolved, and by then it has already processed the cascade and has thrown away any potential fallbacks.

I’m used to being able to rely on the cascade. Let’s say I’m going to set a background colour on paragraphs:

p {
  background-color: red;
  background-color: color(display-p3 1 0 0);
}

First I’ve set a background colour using a good ol’ fashioned keyword, supported in browsers since day one. Then I declare the background colour using the new-fangled color() function which is supported in very few browsers. That’s okay though. I can confidently rely on the cascade to fall back to the earlier declaration. Paragraphs will still have a red background colour.

But if I store the background colour in a custom property, I can no longer rely on the cascade.

:root {
  --myvariable: color(display-p3 1 0 0);
}
p {
  background-color: red;
  background-color: var(--myvariable);
}

All I’ve done is swapped out the hard-coded color() value for a custom property but now the browser behaves differently. Instead of getting a red background colour, I get the browser default value. As Lea explains:

…it will make the property invalid at computed value time.

The spec says:

When this happens, the computed value of the property is either the property’s inherited value or its initial value depending on whether the property is inherited or not, respectively, as if the property’s value had been specified as the unset keyword.

So if a browser doesn’t understand the color() function, it’s as if I’ve said:

background-color: unset;

This took me by surprise. I’m so used to being able to rely on the cascade in CSS—it’s one of the most powerful and most useful features in this programming language. Could it be, I wondered, that the powers-that-be have violated the principle of least surprise in specifying this behaviour?

But a note in the spec explains further:

Note: The invalid at computed-value time concept exists because variables can’t “fail early” like other syntax errors can, so by the time the user agent realizes a property value is invalid, it’s already thrown away the other cascaded values.

Ah, right! So first of all browsers figure out the cascade and then they evaluate custom properties. If a custom property evaluates to gobbledygook, it’s too late to figure out what the cascade would’ve fallen back to.

Thinking about it, this makes total sense. Remember that CSS custom properties aren’t like Sass variables. They aren’t evaluated once and then set in stone. They’re more like let than const. They can be updated in real time. You can update them from JavaScript too. It’s entirely possible to update CSS custom properties rapidly in response to events like, say, the user scrolling or moving their mouse. If the browser had to recalculate the cascade every time a custom property didn’t evaluate correctly, I imagine it would be an enormous performance bottleneck.

So even though this behaviour surprised me at first, it makes sense on reflection.

I’ve probably done a terrible job explaining the behaviour here, so I’ve made a Codepen. Although that may also do an equally terrible job.

(Thanks to Amber for talking through this with me and encouraging me to blog about it. And thanks to Lea for expanding my mind. Again.)

Saturday, June 6th, 2020

Hybrid positioning with CSS variables and max() – Lea Verou

Yet another clever technique from Lea. But I’m also bookmarking this one because of something she points out about custom properties:

The browser doesn’t know if your property value is valid until the variable is resolved, and by then it has already processed the cascade and has thrown away any potential fallbacks.

That explains an issue I was seeing recently! I couldn’t understand why an older browser wasn’t getting the fallback I had declared earlier in the CSS. Turns out that custom properties mess with that expectation.

Monday, June 1st, 2020

Global and Component Style Settings with CSS Variables — Sara Soueidan

Sara shares how she programmes with custom properties in CSS. It sounds like her sensible approach aligns quite nicely with Andy’s CUBE CSS methodology.

Oh, and she’s using Fractal to organise her components:

I’ve been using Fractal for a couple of years now. I chose it over other pattern library tools because it fit my needs perfectly — I wanted a tool that was unopinionated and flexible enough to allow me to set up and structure my project the way I wanted to. Fractal fit the description perfectly because it is agnostic as to the way I develop or the tools I use.

Sass Color Functions in CSS | Jim Nielsen’s Weblog

I’m not the only one swapping out Sass with CSS for colour functions:

Because of the declarative nature of CSS, you’re never going to get something as terse as what you could get in Sass. So sure, you’re typing more characters. But you know what you’re not doing? Wrangling build plugins and updating dependencies to get Sass to build. What you write gets shipped directly to the browser and works as-is, now and for eternity. It’s hard to say that about your Sass code.

Saturday, May 30th, 2020

Programming CSS to perform Sass colour functions

I wrote recently about moving away from Sass to using native CSS features. I had this to say on the topic of mixins in Sass:

These can be very useful, but now there’s a lot that you can do just in CSS with calc(). The built-in darken() and lighten() mixins are handy though when it comes to colours.

I know we will be getting these in the future but we’re not there yet with CSS.

Anyway, I had all this in the back of my mind when I was reading Lea’s excellent feature in this month’s Increment: A user’s guide to CSS variables. She’s written about a really clever technique of combining custom properites with hsl() colour values for creating colour palettes. (See also: Una’s post on dynamic colour theming with pure CSS.)

As so often happens when I’m reading something written by Lea—or seeing her give a talk—light bulbs started popping over my head (my usual response to Lea’s knowledge bombs is either “I didn’t know you could do that!” or “I never thought of doing that!”).

I immediately set about implementing this technique over on The Session. The trick here is to use separate custom properties for the hue, saturation, and lightness parts of hsl() colour values. Then, when you want to lighten or darken the colour—say, on hover—you can update the lightness part.

I’ve made a Codepen to show what I’m doing.

Let’s say I’m styling a button element. I make custom propertes for hsl() values:

button {
  --button-colour-hue: 19;
  --button-colour-saturation: 82%;
  --button-colour-lightness: 38%;
  background-color: hsl(
    var(--button-colour-hue),
    var(--button-colour-saturation),
    var(--button-colour-lightness)
  );
}

For my buttons, I want the borders to be slightly darker than the background colour. When I was using Sass, I used the darken() function to this. Now I use calc(). Here’s how I make the borders 10% darker:

border-color: hsl(
  var(--button-colour-hue),
  var(--button-colour-saturation),
  calc(var(--button-colour-lightness) - 10%)
);

That calc() function is substracting a percentage from a percentage: 38% minus 10% in this case. The borders will have a lightness of 28%.

I make the bottom border even darker and the top border lighter to give a feeling of depth.

On The Session there’s a “cancel” button style that’s deep red.

Here’s how I set its colour:

.cancel {
  --button-colour-hue: 0;
  --button-colour-saturation: 100%;
  --button-colour-lightness: 40%;
}

That’s it. The existing button declarations take care of assigning the right shades for the border colours.

Here’s another example. Site admins see buttons for some actions only available to them. I want those buttons to have their own colour:

.admin {
  --button-colour-hue: 45;
  --button-colour-saturation: 100%;
  --button-colour-lightness: 40%;
}

You get the idea. It doesn’t matter how many differently-coloured buttons I create, the effect of darkening or lightening their borders is all taken care of.

So it turns out that the lighten() and darken() functions from Sass are available to us in CSS by using a combination of custom properties, hsl(), and calc().

I’m also using this combination to lighten or darken background and border colours on :hover. You can poke around the Codepen if you want to see that in action.

I love seeing the combinatorial power of these different bits of CSS coming together. It really is a remarkably powerful programming language.

Global CSS options with custom properties | @mdo

This is clever—using custom properties to enable if/else logic in CSS.

Tuesday, May 19th, 2020

Measuring Performance behind consent popups – Simon Hearne

  • Opted out experiences are ~35% faster
  • Opting in downloads 2.5MB of additional JavaScript
  • Opted in repeat views are twice as slow as opted out

Thursday, April 30th, 2020

Prioritizing users in a crisis: Building the California COVID-19 response site

This is a great case study of the excellent California COVID-19 response site. Accessibility and performance are the watchwords here.

Want to know their secret weapon?

A $20 device running Android 9, with no contract commitment has been one of the most useful and effective tools in our effort to be accessible.

Leaner, faster sites benefit everybody, but making sure your applications run smoothly on low-end hardware makes a massive difference for those users.

Tuesday, April 28th, 2020

Design Can Change the World - But It’s Up to Us to Make it So by Daniel Burka

There is a huge world out there where design isn’t embraced, where designers are clawing for resources, and where design isn’t prioritized. Most of the organizations that are changing your world don’t know much about design, aren’t looking for designers, and won’t even understand what designers are talking about when they show up at the front door.

Monday, April 27th, 2020

Principles and priorities

I think about design principles a lot. I’m such a nerd for design principles, I even have a collection. I’m not saying all of the design principles in the collection are good—far from it! I collect them without judgement.

As for what makes a good design principle, I’ve written about that before. One aspect that everyone seems to agree on is that a design principle shouldn’t be an obvious truism. Take this as an example:

Make it usable.

Who’s going to disagree with that? It’s so agreeable that it’s practically worthless as a design principle. But now take this statement:

Usability is more important than profitability.

Ooh, now we’re talking! That’s controversial. That’s bound to surface some disagreement, which is a good thing. It’s now passing the reversability test—it’s not hard to imagine an endeavour driven by the opposite:

Profitability is more important than usability.

In either formulation, what makes these statements better than the bland toothless agreeable statements—“Usability is good!”, “Profitability is good!”—is that they introduce the element of prioritisation.

I like design principles that can be formulated as:

X, even over Y.

It’s not saying that Y is unimportant, just that X is more important:

Usability, even over profitability.

Or:

Profitability, even over usability.

Design principles formulated this way help to crystalise priorities. Chris has written about the importance of establishing—and revisiting—priorities on any project:

Prioritisation isn’t and shouldn’t be a one-off exercise. The changing needs of your customers, the business environment and new opportunities from technology mean prioritisation is best done as a regular activity.

I’ve said it many times, but one on my favourite design principles comes from the HTML design principles. The priority of consitituencies (it’s got “priorities” right there in the name!):

In case of conflict, consider users over authors over implementors over specifiers over theoretical purity.

Or put another way:

  • Users, even over authors.
  • Authors, even over implementors.
  • Implementors, even over specifiers.
  • Specifiers, even over theoretical purity.

When it comes to evaluating technology for the web, I think there are a number of factors at play.

First and foremost, there’s the end user. If a technology choice harms the end user, avoid it. I’m thinking here of the kind of performance tax that a user has to pay when developers choose to use megabytes of JavaScript.

Mind you, some technologies have no direct effect on the end user. When it comes to build tools, version control, toolchains …all the stuff that sits on your computer and never directly interacts with users. In that situation, the wants and needs of developers can absolutely take priority.

But as a general principle, I think this works:

User experience, even over developer experience.

Sadly, I think the current state of “modern” web development reverses that principle. Developer efficiency is prized above all else. Like I said, that would be absolutely fine if we’re talking about technologies that only developers are exposed to, but as soon as we’re talking about shipping those technologies over the network to end users, it’s negligent to continue to prioritise the developer experience.

I feel like personal websites are an exception here. What you do on your own website is completely up to you. But once you’re taking a paycheck to make websites that will be used by other people, it’s incumbent on you to realise that it’s not about you.

I’ve been talking about developers here, but this is something that applies just as much to designers. But I feel like designers go through that priority shift fairly early in their career. At the outset, they’re eager to make their mark and prove themselves. As they grow and realise that it’s not about them, they understand that the most appropriate solution for the user is what matters, even if that’s a “boring” tried-and-tested pattern that isn’t going to wow any fellow designers.

I’d like to think that developers would follow a similar progression, and I’m sure that some do. But I’ve seen many senior developers who have grown more enamoured with technologies instead of honing in on the most appropriate technology for end users. Maybe that’s because in many organisations, developers are positioned further away from the end users (whereas designers are ideally being confronted with their creations being used by actual people). If a lead developer is focused on the productivity, efficiency, and happiness of the dev team, it’s no wonder that their priorities end up overtaking the user experience.

I realise I’m talking in very binary terms here: developer experience versus user experience. I know it’s not always that simple. Other priorities also come into play, like business needs. Sometimes business needs are in direct conflict with user needs. If an online business makes its money through invasive tracking and surveillance, then there’s no point in having a design principle that claims to prioritise user needs above all else. That would be a hollow claim, and the design principle would become worthless.

Because that’s the point with design principles. They’re there to be used. They’re not a nice fluffy exercise in feeling good about your work. The priority of constituencies begins, “in case of conflict” and that’s exactly when a design principle matters—when it’s tested.

Suppose someone with a lot of clout in your organisation makes a decision, but that decision conflicts with your organisations’s design principles. Instead of having an opinion-based argument about who’s right or wrong, the previously agreed-upon design principles allow you to take ego out of the equation.

Prioritisation isn’t easy, and it gets harder the more factors come into play: user needs, business needs, technical constraints. But it’s worth investing the time to get agreement on the priority of your constituencies. And then formulate that agreement into design principles.

Tuesday, March 3rd, 2020

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

Currying in CSS? | Trys Mudford

I don’t understand what currying is, but Trys points out a really interesting thing about custom properties in CSS:

The value after the : in the CSS custom property does not have to be valid CSS.

That means you can use custom properties to store arbitrary strings of text, which can then be combined within a calc() function, at which point they get evaluated.

Monday, February 24th, 2020

Le Corbusier: How A Utopic Vision Became Pathological In Practice | Orange Ticker

Through planning and architectural design, Le Corbusier hoped to create a scientifically rational and comprehensive solution to urban problems in a way that would both promote democracy and quality of life. For him, the factory production process applied to high-rise buildings with prefabricated and standardized components is the most modern and egalitarian of urban forms.

Something something top-down design systems.

Tuesday, February 18th, 2020

Utopia

Trys and James recently unveiled their Utopia project. They’ve been tinkering away at it behind the scenes for quite a while now.

You can check out the website and read the blog to get the details of how it accomplishes its goal:

Elegantly scale type and space without breakpoints.

I may well be biased, but I really like this project. I’ve been asking myself why I find it so appealing. Here are a few of the attributes of Utopia that strike a chord with me…

It’s collaborative

Collaboration is at the heart of Clearleft’s work. I know everyone says that, but we’ve definitely seen a direct correlation: projects with high levels of collaboration are invariably more successful than projects where people are siloed.

The genesis for Utopia came about after Trys and James worked together on a few different projects. It’s all too easy to let design and development splinter off into their own caves, but on these projects, Trys and James were working (literally) side by side. This meant that they could easily articulate frustrations to one another, and more important, they could easily share their excitement.

The end result of their collaboration is some very clever code. There’s an irony here. This code could be used to discourage collaboration! After all, why would designers and developers sit down together if they can just pass these numbers back and forth?

But I don’t think that Utopia will appeal to designers and developers who work in that way. Born in the spirit of collaboration, I suspect that it will mostly benefit people who value collaboration.

It’s intrinsic

If you’re a control freak, you may not like Utopia. The idea is that you specify the boundaries of what you’re trying to accomplish—minimum/maximum font sizes, minumum/maximum screen sizes, and some modular scales. Then you let the code—and the browser—do all the work.

On the one hand, this feels like surrending control. But on the other hand, because the underlying system is so robust, it’s a way of guaranteeing quality, even in situations you haven’t accounted for.

If someone asks you, “What size will the body copy be when the viewport is 850 pixels wide?”, your answer would have to be “I don’t know …but I do know that it will be appropriate.”

This feels like a very declarative way of designing. It reminds me of the ethos behind Andy and Heydon’s site, Every Layout. They call it algorithmic layout design:

Employing algorithmic layout design means doing away with @media breakpoints, “magic numbers”, and other hacks, to create context-independent layout components. Your future design systems will be more consistent, terser in code, and more malleable in the hands of your users and their devices.

See how breakpoints are mentioned as being a very top-down approach to layout? Remember the tagline for Utopia, which aims for fluid responsive design?

Elegantly scale type and space without breakpoints.

Unsurprisingly, Andy really likes Utopia:

As the co-author of Every Layout, my head nearly fell off from all of the nodding when reading this because this is the exact sort of approach that we preach: setting some rules and letting the browser do the rest.

Heydon describes this mindset as automating intent. I really like that. I think that’s what Utopia does too.

As Heydon said at Patterns Day:

Be your browser’s mentor, not its micromanager.

The idea is that you give it rules, you give it axioms or principles to work on, and you let it do the calculation. You work with the in-built algorithms of the browser and of CSS itself.

This is all possible thanks to improvements to CSS like calc, flexbox and grid. Jen calls this approach intrinsic web design. Last year, I liveblogged her excellent talk at An Event Apart called Designing Intrinsic Layouts.

Utopia feels like it has the same mindset as algorithmic layout design and intrinsic web design. Trys and James are building on the great work already out there, which brings me to the final property of Utopia that appeals to me…

It’s iterative

There isn’t actually much that’s new in Utopia. It’s a combination of existing techniques. I like that. As I said recently:

I’m a great believer in the HTML design principle, Evolution Not Revolution:

It is better to evolve an existing design rather than throwing it away.

First of all, Utopia uses the idea of modular scales in typography. Tim Brown has been championing this idea for years.

Then there’s the idea of typography being fluid and responsive—just like Jason Pamental has been speaking and writing about.

On the code side, Utopia wouldn’t be possible without the work of Mike Reithmuller and his breakthroughs on responsive and fluid typography, which led to Tim’s work on CSS locks.

Utopia takes these building blocks and combines them. So if you’re wondering if it would be a good tool for one of your projects, you can take an equally iterative approach by asking some questions…

Are you using fluid type?

Do your font-sizes increase in proportion to the width of the viewport? I don’t mean in sudden jumps with @media breakpoints—I mean some kind of relationship between font size and the vw (viewport width) unit. If so, you’re probably using some kind of mechanism to cap the minimum and maximum font sizes—CSS locks.

I’m using that technique on Resilient Web Design. But I’m not changing the relative difference between different sized elements—body copy, headings, etc.—as the screen size changes.

Are you using modular scales?

Does your type system have some kind of ratio that describes the increase in type sizes? You probably have more than one ratio (unlike Resilient Web Design). The ratio for small screens should probably be smaller than the ratio for big screens. But rather than jump from one ratio to another at an arbitrary breakpoint, Utopia allows the ratio to be fluid.

So it’s not just that font sizes are increasing as the screen gets larger; the comparative difference is also subtly changing. That means there’s never a sudden jump in font size at any time.

Are you using custom properties?

A technical detail this, but the magic of Utopia relies on two powerful CSS features: calc() and custom properties. These two workhorses are used by Utopia to generate some CSS that you can stick at the start of your stylesheet. If you ever need to make changes, all the parameters are defined at the top of the code block. Tweak those numbers and watch everything cascade.

You’ll see that there’s one—and only one—media query in there. This is quite clever. Usually with CSS locks, you’d need to have a media query for every different font size in order to cap its growth at the maximum screen size. With Utopia, the maximum screen size—100vw—is abstracted into a variable (a custom property). The media query then changes its value to be the upper end of your CSS lock. So it doesn’t matter how many different font sizes you’re setting: because they all use that custom property, one single media query takes care of capping the growth of every font size declaration.

If you’re already using CSS locks, modular scales, and custom properties, Utopia is almost certainly going to be a good fit for you.

If you’re not yet using those techniques, but you’d like to, I highly recommend using Utopia on your next project.

Tuesday, February 11th, 2020

Fluid scale and tokens: a match made in heaven - Andy Bell

Andy takes Utopia for a spin—it very much matches his approach.