An experimental signal-based UI library with JSX and React-shaped hooks. Components run once per mount; reactive bindings update the DOM directly. Keyed lists compile to direct insert/move/remove operations instead of reconciliation.
The compiler accepts a checked subset of ordinary React source and rejects the rest with an explicit diagnostic. It is not a general React implementation: arbitrary components, libraries and features outside that subset are unsupported. See Compatibility and the supported scope and evidence.
runOnce is the default. Each component body executes once per mount, state
reads compile to reactive bindings, and list updates become direct operations,
with no keyed reconciler calls. Source outside the supported subset is rejected
at build time rather than mis-compiled.
Passing runOnce: false selects the older path, which wraps reactive reads and
uses the reconciling list() renderer. State there is a getter, so it is read
as count(). The two paths do not share those semantics; pick one per build.
import { useState } from '@rrjs/react-compat'
import { mount } from '@rrjs/renderer'
function Counter() {
const [count, setCount] = useState(0)
return (
<button onClick={() => setCount(count + 1)}>
Clicked {count} times
</button>
)
}
mount(Counter, document.getElementById('app')!)The component source is ordinary React. One difference in behaviour:
- The component function runs once when mounted, not on every state change — the signal updates the DOM directly.
On the runOnce: false path count is a getter instead, read as count(). The default path reports that spelling as a build error rather than letting it fail on the first click.
Other React APIs have important semantic differences; see the compatibility document before migrating an application.
npm install @rrjs/signals @rrjs/renderer @rrjs/react-compat
npm install -D @rrjs/babel-plugin @babel/core @babel/preset-typescriptThe packages are ES modules. import works everywhere they run. require(),
and naming the plugin in a Babel configuration that is used synchronously (for
example by babel-jest), rely on Node's support for loading ES modules with
require, which Node documents from 20.19 and 22.12. That path is verified on
Node 24.13.1. Use 0.2.1 or later: 0.2.0 kept Node processes from exiting and
could not be required.
See docs/MIGRATION.md for Vite, Webpack, and esbuild setup.
| Package | Purpose | Tests |
|---|---|---|
@rrjs/signals |
Reactive primitives: createSignal, effect, computed, batch |
53 |
@rrjs/renderer |
DOM renderer, direct list operations, and the reconciling list() used by runOnce: false |
76 |
@rrjs/react-compat |
React hooks API on top of signals | 111 |
@rrjs/babel-plugin |
Compiles React components to run once, with direct DOM updates | 48 |
Total: 288 package tests, 0 failing, 0 skipped. A further 175 integration
tests across 19 files run from apps/compat-audit (npm test --prefix apps/compat-audit),
and every test in both suites asserts a result. Run node scripts/test-all.mjs for
current package results. Test counts alone do not establish React compatibility.
Historical measurements and raw artifacts are available in docs/BENCHMARKS.md and bench-results/. They are not current-branch measurements. Runtime correctness fixes change the measured implementation; performance must be rerun after behavior matches.
There is no virtual DOM. There is no reconciliation pass on every render. Components run once when mounted; updates happen through fine-grained reactive bindings.
┌─────────────────────────────────────────┐
│ Your application code │ <App />, hooks, JSX
├─────────────────────────────────────────┤
│ @rrjs/babel-plugin │ compiles JSX to h()
├─────────────────────────────────────────┤
│ @rrjs/react-compat │ useState, useEffect, ...
├─────────────────────────────────────────┤
│ @rrjs/renderer │ h(), mount(), list()
├─────────────────────────────────────────┤
│ @rrjs/signals │ createSignal, computed, effect
└─────────────────────────────────────────┘
When you call useState(0), you get a signal getter and setter. When the renderer encounters a JSX expression that reads the getter, it wires an effect that subscribes to the signal and updates only the relevant DOM node when the signal changes. The component function itself never runs again.
Full architectural deep-dive in docs/HOW-IT-WORKS.md.
| Hook | Status |
|---|---|
useState, useReducer, useMemo, useCallback, useRef |
✓ Identical semantics |
useEffect, useLayoutEffect, useInsertionEffect |
✓ Identical timing |
useContext, createContext |
✓ Identical |
useId, useImperativeHandle, useSyncExternalStore, forwardRef |
✓ Identical |
useTransition, useDeferredValue, useDebugValue |
⚠ No-ops (no scheduler) |
| React DevTools | ✗ Not supported (no fiber tree) |
| Server-side rendering | ✗ v0.2 milestone |
| Class components | ✗ Hooks only |
See docs/COMPAT.md for the full compatibility contract.
docs/COMPAT.md— what works, what doesn't, what differsdocs/HOW-IT-WORKS.md— architecture walkthroughdocs/EFFECT-TIMING.md—useEffectvsuseLayoutEffectdeep divedocs/MIGRATION.md— Vite/Webpack setup, code translation patternsBENCHMARKS.md— full benchmark methodology and results
apps/demo— minimal counter with JSX and hooksapps/todomvc— TodoMVC example; localStorage update effects still need compatibility workapps/benchmark— js-framework-benchmark adapter
To run TodoMVC locally:
git clone https://github.com/SamAbaasi/reactive-react
cd reactive-react/apps/todomvc
npm install
npm run devMIT © Saman Abaasi
Copyright (c) 2026 Saman Abaasi
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.