Building accessible and resilient web applications is crucial to providing a good user experience. Progressive enhancement is a development approach that focuses on core content and functionality first, then progressively adding enhancements to elevate the experience. In this post, we’ll look at implementing progressive enhancement with JavaScript and the SvelteKit framework to create an accessible web app.
The core philosophy behind progressive enhancement is that websites should work for all users, regardless of their device, browser choice or capabilities. By starting with content and basic functionality using proper HTML semantics, then layering on CSS for presentation and JavaScript for interactivity, you create a solid foundation that “just works”, then incrementally make it better for capable devices.
This is fundamentally about accessibility. Users on older devices or browsers that don’t support all the latest features still get complete access to the content and core functions. Those on modern devices get an enhanced experience. It's the best of both worlds!
So how does this work in practice? Let's walk through building a web app with SvelteKit using a progressive enhancement approach.
First, we focus on the core HTML structure and content without any styling or logic added in. The HTML should use proper semantic elements like header, nav, main, footer. All content should be well-structured and all core functions like navigation and forms should work properly.
Next, we add styling with CSS to enhance the visual design. This improves the look and feel without affecting the underlying HTML structure. If for some reason the CSS fails to load, the content is still perfectly accessible.
Finally, we use JavaScript to add interactivity, dynamic features, and overall enhance the experience. For example, we could use Svelte's capabilities to add animated transitions, fetch data from an API, or enable client-side routing. But if the JS isn’t supported, the core functionality still remains intact.
Progressively building up the experience in layers like this takes a bit more planning up front. But the end result is an app that provides a great experience for modern devices, while still being usable and accessible across the board. The content and core functions work everywhere, even if CSS and JS fail, ensuring resilience.
By embracing progressive enhancement as a development strategy, you can build web apps that provide value to all your users. The web is an open platform with diverse capabilities. Planning for resilience and accessibility from the start ensures we don’t exclude users and provide quality experiences tailored to each device.
