Table of contents

1. 🧠 What is reactivity?
2. ⚛️ React: State-based re-rendering
3. How does it work?
4. Pros:
5. Cons:
6. 🧩 Vue: Proxy-Based Reactivity
7. How does it work?
8. Pros:
9. Cons:
10. ⚡ SolidJS: Thin and direct reactivity in the DOM
11. How does it work?
12. Pros:
13. Cons:
14. 🔍 Direct comparison
15. 🧭 Which one to choose?
16. 🧶 Conclusion

Comparing the reactive systems of the three main modern frontend approaches

The construction of modern interfaces directly depends on the way the framework deals with state changes — that is, its reactivity system. Three major players stand out with very different approaches:

• React, widely used, based on component re-rendering.
• Vue, which combines automatic reactivity with optimized rendering.
• SolidJS, which goes further, with fine reactivity and no component re-renders.

In this article, we will compare the reactive systems of each one and understand the practical implications of this on development and performance.

🧠 What is reactivity?

Reactivity is the ability to detect changes in the application state and update the interface automatically and efficiently.

Example: you click a button to increment a number. Reactivity ensures that the number displayed on the screen will update with the new value.

---

⚛️ React: State-based re-rendering

How does it work?

React uses hooks, like useState and useEffect, and whenever a state changes via setState, the entire component is re-rendered.

function Counter() {
  const [count, setCount] = useState(0);
  return (
    <div>
      <p>{count}</p>
      <button onClick={() => setCount(count + 1)}>+</button>
    </div>
  );
}

• setCount re-renders the entire Counter component.
• React compares the new virtual DOM with the previous one (diffing) and updates the real DOM.

Pros:

• Simple to understand.
• Predictable flow (re-render = new UI).

Cons:

• It may re-render more than necessary.
• Needs manual optimizations (memo, useCallback, useMemo).

---

🧩 Vue: Proxy-Based Reactivity

How does it work?

Vue uses Proxies (Vue 3) to observe changes in data (reactive, ref) and automatically updates only the parts of the template that depend on this data.

<template>
  <p>{{ count }}</p>
  <button @click="count++">+</button>
</template>

<script setup>
import { ref } from 'vue'
const count = ref(0)
</script>

• Vue tracks that <p> depends on count, so only that part will be updated.

Pros:

• Automatic reactivity.
• Granularity per section of the template.
• Less need for manual optimizations.

Cons:

• Tracking logic can be too invisible.
• Reactivity with reactive() has some pitfalls (e.g. .value, deep proxies).

---

⚡ SolidJS: Thin and direct reactivity in the DOM

How does it work?

SolidJS uses a reactivity system inspired by signals. When a createSignal changes, only the DOM directly dependent on that signal is updated. No components are re-rendered.

import { createSignal } from "solid-js";

function Counter() {
  const [count, setCount] = createSignal(0);
  return (
    <div>
      <p>{count()}</p>
      <button onClick={() => setCount(count() + 1)}>+</button>
    </div>
  );
}

• count() is a signal, and Solid knows exactly where it is being used.
• No re-renders. Only <p> is updated directly in the DOM.

Pros:

• Very high performance.
• Zero over-yield.
• Less need for memorization or manual optimizations.

Cons:

• Reactive syntax requires a change of mindset (e.g. count() instead of count).
• Harder to debug in very complex apps (tools still maturing).

---

🔍 Direct comparison

Appearance	React	See	SolidJS
Reactivity model	Imperative via hooks	Declarative with proxies	Signals + fine reactivity
Component re-rendering	Yes	Yes (but optimized)	No
Update Granularity	Average	High	Maximum
Virtual DOM	Yes	Yes	Does not use
Performance	Good, with manual optimizations	Very good	Extremely fast
Initial ergonomics	Familiar but verbose	Balanced and intuitive	A little out of the norm

---

🧭 Which one to choose?

It depends on your objective:

• React is great if you’re looking for a vast ecosystem, enterprise support, and predictability.
• Vue offers a balance between simplicity, performance and productivity.
• SolidJS is ideal if you want maximum performance with minimal re-rendering, and are willing to adopt a more reactive mindset from the start.

---

🧶 Conclusion

The future of the frontend is moving towards finer, more predictable and performant reactivity models. SolidJS shows that it is possible to write reactive code without re-rendering components — and still maintain a developer-friendly API.

React and Vue continue to evolve: React is experimenting with signals (with React Canary) and Vue continues to improve its reactive system.

In the end, knowing how each framework deals with reactivity makes you a more aware developer — and prepared to choose the best tool for each challenge.