blog

26th April 2022

Working with reduced motion in Svelte


Accessibility on the web is important. It’s why frameworks like Svelte have accessibility warnings built in, and why it’s a metric in tools such as lighthouse. You want the ability to control the look and feel of your website for those who use assistive technology, or just want a better experience on the web.

Animations in Svelte are powerful, but for those who prefer reduced motion, some aren’t ideal. A solution to this problem isn’t exactly new. Geoff Rich published a blog post on it back in March 2021. However, I’m lazy and don’t want to implement this on every project. This led me to make svelte-reduced-motion.

I recommend reading this awesome CSS Tricks Article by Eric Bailey. It goes in depth about the benefits people can get from sites that support reduced motion and the prefers-reduced-motion media query.

Getting Started

As per usual, let’s install the dependency.

npm install svelte-reduced-motion -D

Transitions

To make it easy, we provide a way to use any of Svelte’s built-in transitions out of the box. Later you will learn how you can create custom ones too! By default, all transitions will fall back to fade when reduced motion is requested.

<script>
  import { fly } from 'svelte-reduced-motion/transition';
</script>

<div transition:fly={{ y: -20 }}>
  I will fly by default, and fade if the user requests reduced motion
</div>

All the transitions from svelte/transition are supported with feature parity.

Custom Transitions

With svelte-reduced-motion, it’s easy to set a fallback transition for users who prefer reduced motion. The signature is simple. We can pass in the desired transition and a fallback. We also have a way of customising the options for each individually (the options we pass in the template are passed to both. In some cases, we might need to configure them individually)

  • Simple Example

    <script>
        import { createTransition } from 'svelte-reduced-motion';
        import { fly } from 'svelte/transition';
    
        const accessibleTransition = createTransition(fly);
    </script>
    
    <!-- You can even specify the options as usual-->
    <div transition:accessibleTransition={{ y: -20 }}>
        Hello world
    </div>
  • Custom options for each transition

    const accessibleTransition = createTransition(
        [fly, { duration: 1000 }], // default
        [fade, { duration: 200 }]  // reduced-motion fallback
    );
    
    const accessibleTransition = createTransition(
        [fly, { duration: 750, y: -20 }],
        fade
    );

Reacting to reduced motion

The last thing we can do with svelte-reduced-motion is react to whether the user prefers reduced motion. For example, we export a reducedMotion store:

<script>
    import { reducedMotion } from 'svelte-reduced-motion';
</script>

<p>
    Reduced Motion: {$reducedMotion ? 'enabled' : 'disabled'}
</p>

Conclusion

Prefers reduced motion is another accessibility item we have to consider in Svelte. CSS provides us with all the tools, and combined with svelte-reduced-motion, we can easily add this consideration to our Svelte projects.