As your Phoenix LiveView app grows, so does the complexity of the user interface — and with that, the risk of tightly coupled state, tangled events, and brittle updates. This is where Phoenix LiveComponents shine.
If you’ve used basic function components in LiveView, you already know the benefits of reusable UI blocks. But LiveComponents take it further: they encapsulate their own state and events, allowing you to isolate complex behavior behind clean interfaces. This becomes essential in larger applications where maintainability, testability, and team collaboration all hinge on well-defined boundaries.
Let’s walk through a practical example of using LiveComponents to isolate behavior: building a self-updating timer. It may seem like a toy problem, but the pattern scales directly to more complex real-world use cases like real-time widgets, polling dashboards, form sections, and background processes.
We’ll define a component that tracks its own time since mount. The component starts ticking the moment it’s connected and increments an internal counter every second — all without any logic in the parent LiveView.
The component initializes its internal seconds state to zero. When it mounts, it schedules a tick message every second. It handles each tick by incrementing the counter and then re-scheduling itself. As the state changes, the component automatically re-renders. From the parent LiveView’s perspective, it’s just a black box — you render it with a unique ID, and it takes care of itself.
This pattern is powerful because it promotes true encapsulation. The parent LiveView doesn’t know or care how the timer works. It doesn’t handle its events, update its state, or even manage its lifecycle. You can reuse this timer across any number of pages, without worrying about state collisions or unexpected behavior. Testing the timer becomes straightforward, since all of its logic lives in one place.
Some developers might wonder why not just use JavaScript to build a timer. That’s a valid question. And in some cases, it makes sense. But keeping this logic in Elixir gives you consistency across clients, better control over clustered deployments, and seamless server-side testing. More importantly, it keeps your mental model unified — everything is in the LiveView world, which makes debugging and extending much easier.
You’ll find that LiveComponents are useful for far more than timers. Think of things like real-time vote counters, chat message panels, file upload progress bars, or editable form sections. Each of these can be isolated into a component that owns its own logic and communicates with the parent only when absolutely necessary.
As you grow more comfortable with LiveComponent design, you’ll begin to treat each component as a mini-app within your UI. You’ll start designing them with contracts in mind — what data they expect, what events they emit, how they handle failure, and how they clean up resources. You’ll spend less time passing assigns around and more time composing robust, testable pieces that can be built, reviewed, and owned by different members of your team.
This kind of isolation becomes even more valuable when working in teams. One developer can build a polling widget while another builds a live form. As long as each is implemented as a self-contained LiveComponent, they can be developed in parallel with little risk of conflict. Bugs are easier to track down, features are easier to reuse, and onboarding new developers becomes much faster.
LiveComponents are not a silver bullet. There are trade-offs to consider, especially when performance or rendering overhead becomes a concern. But used wisely, they offer a way to bring clarity and structure to what could otherwise become a tangled mess of state and callbacks.
If you’re building Phoenix LiveView apps that need to scale not just technically but in terms of team and process, I’ve written a detailed PDF guide: Phoenix LiveView: The Pro’s Guide to Scalable Interfaces and UI Patterns. It’s a 20-page manual for designing LiveView apps that are maintainable, testable, and ready for collaboration. Whether you’re solo or part of a team, this guide will help you build LiveView systems that are a joy to work on — today and in the future.
