The story of modern frontend frameworks has always revolved around change — how to detect it, represent it, and respond to it efficiently.
React built its entire philosophy on a simple but powerful assumption:
Changes in data and component state are unpredictable.
To cope with this uncertainty, React introduced the Virtual DOM —
a clever mechanism that continuously compares previous and current UI trees to decide what needs to be re-rendered.
But this design, while revolutionary in 2013, also came with a price.
The constant diffing adds overhead, and in large-scale applications, the cost becomes increasingly visible.
So here’s a question worth asking:
What if that assumption was wrong?
If data changes could be observed precisely, would we still need the Virtual DOM at all?
That’s the core idea behind Signals and Fine-grained Reactivity —
a model where data itself is observable.
Instead of diffing entire trees, we update only the exact parts that depend on the changed value.
No guessing. No reconciliation. Just direct, deterministic updates.
This philosophy echoes what Ryan Carniato, the creator of Solid.js, often calls “reactivity without illusion.”
Back in 2012, React’s trade-offs made perfect sense.
But today, with frameworks like Svelte, Solid, and Vue 3 pushing the boundaries of compiler-driven or signal-based reactivity,
the Virtual DOM may have served its purpose as a transitional technology —
a bridge toward something more fundamental.
What This Series Is About?
In this 30-part series, we’ll dive deep into the mechanics, architecture, and design philosophy of Signals and fine-grained reactivity.
We’ll start from first principles — building a tiny reactive core from scratch — and gradually extend it into a full system with scheduler, graph management, atomic transactions, and even DevTools integration.
Along the way, we’ll compare how frameworks like React, Vue, and Solid handle reactivity differently,
and how concepts like lifecycles, effects, and dependencies can be unified under a single mental model.
This series is inspired by my open-source project, segnale-react,
and my long-term goal is to make these ideas approachable, practical, and framework-agnostic.
Why You Should Keep Reading?
By the end of this journey, you’ll understand not just how Signals work,
but why this paradigm fundamentally changes how we think about state, rendering, and performance in modern frontend architecture.
The next article begins right at the core —
what a signal actually is, how it stores and propagates state,
and why fine-grained means more than just “efficient.”
Stay tuned.
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