Snippets

These snippets are my attempt to save and organize various bits of code, best practices, and resources relating to web development and design. They also function as a to do list of sorts, for things I want to implement in my own code, but haven’t yet. The concept is inspired by Jeremy Keith’s links and CSS-Tricks, among other things. Enjoy.

Using notifications responsibly

We see an increasing number of websites using notifications irresponsibly. The moment you visit the site, you get prompted by the browser to sign up for notifications. Not only is it annoying to be asked immediately, but it is unlikely to be effective.

We wanted to set a good example for responsible use of push notifications. So we don’t ask for permission to send push notifications until the user selects the button asking to turn notifications on. And we only provide the option to subscribe at the bottom of articles.

Screenshot of Cloud Four's options to subscribe to new articles via either web notifications or email

Once someone selects that button, then we trigger the browser alert asking for permission to send notifications. If the person signs up, we send a quick notification thanking them and update the button to indicate how they can turn off notifications.

Cloud Four's Get Notifications button turns into a Turn Off Notifications button after turning on notifications.

For more on using web notifications responsibly, we recommend Best Practices for Push Notifications Permissions UX by Owen Campbell-Moore.

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Premonish - A library for predicting what element a user will interact with next.

A screenshot of the Premonish page, with different coloured squares in the center, top left, bottom left, and bottom right, along with the Premonish header and some descriptive text " Premonish - A library for predicting what element a user will interact with next."

This is really cool. This library seems to use the pointer’s trajectory to predict what you’re heading towards, and highlights the appropriate cube. I suspect this only works with pointers that can be detected as moving, like mice and styluses that have that capability, but probably does nothing useful with touch in most cases. Either way, give it a shot, it’s eerie. The most obvious use case for this is to pre-load a link if the user starts to head for it, but of course that has the side effect of possibly wasting the user’s data if they’re on a capped connection.

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Performant Parallaxing

Love it or hate it, parallaxing is here to stay. When used judiciously it can add depth and subtlety to a web app. The problem, however, is that implementing parallaxing in a performant way can be challenging. In this article we’ll discuss a solution that is both performant and, just as importantly, works cross-browser.

An abstracted view of what a CSS parallax effect would look like if the layers were to lift up off of the screen, and you could step to the side to see them in three axes, with arrows showing the layers moving up and down along the X axis.

TL;DR

  • Don’t use scroll events or background-position to create parallax animations.
  • Use CSS 3D transforms to create a more accurate parallax effect.
  • For Mobile Safari use position: sticky to ensure that the parallax effect gets propagated.

[…]

Both Scott Kellum and Keith Clark have done significant work in the area of using CSS 3D to achieve parallax motion, and the technique they use is effectively this:

  • Set up a containing element to scroll with overflow-y: scroll (and probably overflow-x: hidden).
  • To that same element apply a perspective value, and a perspective-origin set to top left, or 0 0.
  • To the children of that element apply a translation in Z, and scale them back up to provide parallax motion without affecting their size on screen.

The CSS for this approach looks like so:

CSS

.container {
  width: 100%;
  height: 100%;
  overflow-x: hidden;
  overflow-y: scroll;
  perspective: 1px;
  perspective-origin: 0 0;
}
 
.parallax-child {
  transform-origin: 0 0;
  transform: translateZ(-2px) scale(3);
}

Which assumes a snippet of HTML like this:

HTML

<div class="container”>
  <div class="parallax-child”></div>
</div>

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Large, custom, accessible checkboxes and radio buttons on GOV.UK

A screenshot of extra large checkboxes and radio buttons on GOV.UK sites

Early in the development of GOV.UK we observed in research how a majority of users would click on radio button or checkbox controls rather than on their labels, despite the fact that the labels are much bigger and therefore easier to click (see Fitt’s Law).

[…]

We reasoned that this was because users didn’t know whether or not they could click on the labels. Many websites don’t let you click on labels, so choosing to always click on the control is perfectly rational user behaviour.

[…]

First we thought we’d try to make it really obvious that you could click our labels, so we coloured them grey and made them respond to the mouse hovering over them.

We thought this would work, so we rolled out the design across services on GOV.UK. We saw again and again though in lab research that most users still clicked on the controls.

[…]

In our latest iteration we’ve replaced the native browser controls with custom ones, which all our supported browsers will get.

We’ve also removed the grey background, as it did not have the effect on user behaviour that it was intended to.

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