transactional-reducer

A state management library that adds transaction support to the reducer pattern. It lets you wrap a group of dispatch operations in a transaction with commit and rollback semantics — just like database transactions.

Features

• Optimistic updates with automatic rollback: Optimistically update state first; changes are automatically reverted if the async operation fails
• Cancellable async tasks: A new transaction with the same ID automatically cancels the previous one, preventing race conditions
• Flexible deduplication strategies: Four strategies — rollback, commit, reuse, and reject
• Nested transactions: Parent and child transactions; children can commit independently or roll back with their parent
• Commit boundaries: A child transaction with onError: "commit" is preserved even when its parent rolls back
• Framework-agnostic: The core engine works in any JavaScript environment

Packages

Package	Description
@transactional-reducer/core	Core engine — framework-agnostic
@transactional-reducer/react	React Hook (useTransactionalReducer)

Quick Start

import { TransactionalReducer } from "@transactional-reducer/core";

const reducer = (state, action) => {
  switch (action.type) {
    case "inc": return { count: state.count + 1 };
    case "dec": return { count: state.count - 1 };
  }
};

const engine = new TransactionalReducer(reducer, { count: 0 });

// Optimistic update with automatic rollback
await engine.run(async (tx) => {
  tx.dispatch({ type: "inc" });
  await fetch("/api/inc");
  // Success → auto-commit; failure → auto-rollback
});

React usage:

import { useTransactionalReducer } from "@transactional-reducer/react";

function Counter() {
  const [state, engine] = useTransactionalReducer(reducer, { count: 0 });

  const handleOptimisticInc = () =>
    engine.run(async (tx) => {
      tx.dispatch({ type: "inc" });
      await fetch("/api/inc");
    });

  return (
    <div>
      <p>{state.count}</p>
      <button onClick={handleOptimisticInc}>+1 (optimistic)</button>
    </div>
  );
}

Development

pnpm install
pnpm build
pnpm test

License

MIT