Proxy State vs useState in React: What’s the Real Difference?

State management is at the heart of every React application. Most developers start with useState, React’s built-in hook for managing component state. But as applications grow, you may hear about something called “proxy state.”

• What is proxy state?
• Why does it feel so different from useState?
• And when should you care?

Let’s break it down.

Understanding useState first

useState is React’s fundamental state API. It works on a snapshot model.

const [count, setCount] = useState(0);
setCount(count + 1);

Every time you update state:

• You don’t mutate the existing value
• You replace it with a new one
• React re-renders the entire component

For objects, this usually means copying:

setUser(prev => ({
...prev,
age: 21
}));

React decides to re-render because the reference changed, not because it knows which property changed.

This model is:

• predictable
• simple
• aligned with functional programming

But it can become verbose and inefficient in large apps.

What “proxy state” means

React itself does not provide “proxy state.”
The term usually refers to state management libraries that use JavaScript Proxies.

Examples include:

• Valtio
• MobX
• some reactive store implementations

A JavaScript Proxy can intercept operations like:

• reading a property
• writing to a property

This lets libraries track:

• what parts of state a component used
• exactly what changed

So instead of replacing state, you mutate it directly.

state.count++;
state.user.name = "Fayaz";

Behind the scenes, the proxy detects these mutations and notifies only the components that depend on those specific properties.

The core difference in mindset

The biggest shift is the mental model.

useState → snapshot-based

• State is immutable
• Updates replace values
• Re-render happens at component level

Proxy state → reactive objects

• State is mutable
• Updates are property-level
• Re-render happens at usage level

You stop thinking in terms of “setting state” and start thinking in terms of “changing state.”

Example: the same logic, two styles

With useState

1const [cart, setCart] = useState({ items: [], total: 0 });
2
3function addItem(item) {
4  setCart(prev => ({
5    ...prev,
6    items: [...prev.items, item],
7    total: prev.total + item.price
8  }));
9}

Here you must:

• copy objects
• manually keep everything in sync
• replace the whole state object

With proxy state (conceptual)

1cart.items.push(item);
2cart.total += item.price;

The proxy:

• detects the mutation
• tracks dependencies
• re-renders only what used cart.items or cart.total

Your code feels closer to plain JavaScript.

Dependency tracking: the hidden superpower

React with useState does not know which properties you accessed.

const name = user.profile.name;

If any part of user changes, the whole component re-renders.

Proxy-based systems track access at runtime:

• Component A reads user.name
• Component B reads user.age
• Only the component using the changed property updates

This is called fine-grained reactivity, and it’s the main technical advantage of proxy state.

Performance implications

• useState → coarse-grained updates
• Proxy state → fine-grained updates

In large apps with deeply nested state, proxy state can significantly reduce unnecessary re-renders.

However, useState is:

• extremely optimized
• simpler to debug
• more predictable in concurrent React

When proxy state shines

Proxy-based state is especially useful when:

• You have large global stores
• Many components consume tiny slices of state
• State is deeply nested
• You want minimal re-rendering
• You prefer mutation-style code

When useState is still the best choice

useState is ideal when:

• State is local to a component
• You’re managing simple UI state
• You want to stick to core React APIs
• You care about explicit, controlled updates

For most UI interactions (forms, toggles, modals), useState is still the cleanest solution.

Proxy state is not Immer

A common confusion: Immer also uses proxies, but it does not create reactive state.

Immer helps you write immutable updates in a mutable style:

1setState(draft => {
2  draft.count++;
3});

But it still returns a new snapshot.
Proxy state libraries keep the proxy object alive and make it reactive.

Final takeaway

Proxy state differs from useState because it uses JavaScript Proxies to:

• track property access
• detect mutations
• trigger fine-grained updates

useState works by replacing values and re-rendering components.
Proxy state works by mutating objects and letting a reactive system decide what should update.

Neither is “better.”
They solve different problems at different scales.