pmndrs/valtio
🧙 Valtio makes proxy-state simple for React and Vanilla
React state management library using JavaScript Proxies for simple mutations
State mutations update proxy objects which notify listeners, React components consume immutable snapshots that trigger re-renders only when accessed properties change
Under the hood, the system uses 2 feedback loops, 2 data pools to manage its runtime behavior.
Structural Verdict
A 10-component library with 23 connections. 101 files analyzed. Highly interconnected — components depend on each other heavily.
How Data Flows Through the System
State mutations update proxy objects which notify listeners, React components consume immutable snapshots that trigger re-renders only when accessed properties change
- Proxy Creation — proxy() wraps objects with change tracking and listener notification
- State Mutation — Direct property assignment triggers proxy traps and listener callbacks
- Snapshot Generation — useSnapshot creates immutable snapshots with read-tracking for render optimization
- Render Triggering — Components re-render only when properties accessed in previous render change
System Behavior
How the system actually operates at runtime — where data accumulates, what loops, what waits, and what controls what.
Data Pools
Mutable proxy objects that accumulate state changes
Version counters for each proxy to track change history
Feedback Loops
- React Re-render Loop (polling, balancing) — Trigger: Property access tracking. Action: Compare accessed properties between renders. Exit: No changes in accessed properties.
- Listener Notification (recursive, reinforcing) — Trigger: Proxy mutation. Action: Notify all registered listeners. Exit: All listeners processed.
Delays & Async Processing
- Async State Updates (async-processing) — setInterval updates proxy state with 200ms intervals
Technology Stack
Primary language with strict typing
UI framework integration via hooks
Build tool for examples and development
Library bundling with multiple output formats
Testing framework for unit tests
Property access tracking for render optimization
Key Components
- proxy (function) — Creates a self-aware proxy object that tracks mutations and notifies listeners
src/vanilla.ts - useSnapshot (hook) — React hook that creates optimized snapshots for render-safe state consumption
src/react.ts - snapshot (function) — Creates immutable snapshots of proxy state at a specific version
src/vanilla.ts - proxyWithHistory (utility) — Extends proxy with undo/redo functionality for time-travel debugging
examples/editor-proxyWithHistory/src/App.tsx - proxyMap (utility) — Proxy wrapper for Map collections enabling reactive Map operations
examples/todo-with-proxyMap/src/store.ts - store (module) — Central state management with actions pattern for todo application
examples/todo-with-proxyMap/src/store.ts - actions (module) — Action functions that mutate the proxy state following Redux-like patterns
examples/todo-with-proxyMap/src/store.ts - useTodos (hook) — Custom hook that derives filtered todo lists from proxy state snapshots
examples/todo-with-proxyMap/src/store.ts - Listener (type-def) — Function signature for proxy change notifications with operation details
src/vanilla.ts - Op (type-def) — Operation type describing set/delete mutations with paths and values
src/vanilla.ts
Configuration
pnpm-workspace.yaml (yaml)
packages(array, unknown) — default: .minimumReleaseAge(number, unknown) — default: 1440
Explore the interactive analysis
See the full architecture map, data flow, and code patterns visualization.
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Frequently Asked Questions
What is valtio used for?
React state management library using JavaScript Proxies for simple mutations pmndrs/valtio is a 10-component library written in TypeScript. Highly interconnected — components depend on each other heavily. The codebase contains 101 files.
How is valtio architected?
valtio is organized into 5 architecture layers: Core Vanilla, React Integration, Utilities, Examples, and 1 more. Highly interconnected — components depend on each other heavily. This layered structure enables tight integration between components.
How does data flow through valtio?
Data moves through 4 stages: Proxy Creation → State Mutation → Snapshot Generation → Render Triggering. State mutations update proxy objects which notify listeners, React components consume immutable snapshots that trigger re-renders only when accessed properties change This pipeline design keeps the data transformation process straightforward.
What technologies does valtio use?
The core stack includes TypeScript (Primary language with strict typing), React (UI framework integration via hooks), Vite (Build tool for examples and development), Rollup (Library bundling with multiple output formats), Vitest (Testing framework for unit tests), proxy-compare (Property access tracking for render optimization). A focused set of dependencies that keeps the build manageable.
What system dynamics does valtio have?
valtio exhibits 2 data pools (Proxy State, Version Tracking), 2 feedback loops, 1 delay. The feedback loops handle polling and recursive. These runtime behaviors shape how the system responds to load, failures, and configuration changes.
What design patterns does valtio use?
4 design patterns detected: Proxy State Management, Actions Pattern, Custom Hooks, Render Optimization.
Analyzed on April 1, 2026 by CodeSea. Written by Karolina Sarna.