Simstate NPM | npm.io

simstate

simstate is a strongly-typed React state management tool favoring React Hooks and TypeScript.

Install

npm install --save simstate

How to use

Talk is cheap. Here is the code. :smile:

import React, { useState, useCallback, useRef } from "react";
import { useStore, StoreProvider, createStore } from "simstate";

// 1. Define your stores as a custom hook.
//    Any hook supported by React is supported here!
function CounterStore(initialValue: number) {
  const [value, setValue] = useState(initialValue);

  const incrementStep = useRef(1).current;
  const increment = useCallback(() => setValue(value + incrementStep), [value]);

  return { value, setValue, increment };
}

// 2. Create a store (Arguments as parameters to the function)
//    Arguments are type-checked so never pass bad arguments!
const counterStore = createStore(CounterStore, 42);

// 3. Wrap your component with StoreProvider
const RootComponent: React.FC = () => (
  <StoreProvider stores={[counterStore]}>
    <MyComponent />
  </StoreProvider>
);

// 4. Pass the store function to useStore to get the store
const MyComponent: React.FC = () => {
  const counterStore = useStore(CounterStore);

  return (
    <div>
      <p>Current: <span>{counterStore.value}</span></p>
      <button onClick={counterStore.increment}>Increment</button>
      <button onClick={() => counterStore.setValue(counterStore.value - 1)}>Decrement</button>
    </div>
  );

Features

Simple APIs and you just read all of them
No dependency but React 16.8 or higher and tslib for TypeScript projects
Strongly typed with TypeScript, and all types can be inferred.
Nested providers. Inner provided stores will override outer stores

v2

Since v3, simstate has been revamped to fully embrace react hooks. Looking for more traditional usage and implementation? Check out v2 branch.

Tips

Check examples for more usage
Name your store with capital letter (AStore), and name with store instance with lowercase letter (aStore). It makes it easy to work with multiple stores in one component.

const MyComponent = () => {
  const aStore = useStore(AStore);
  const bStore = useStore(BStore);
  // ...
}

Store instance is immutable. Every time a state is changed, a new store instance is created. Therefore, when store instance is used in combination with your custom hook, make sure that store instance is one of your hook deps. (examples/immutable_store_instance.tsx)

Simstate and Why (English): This article talks about why I write this library. simstate-i18n: A Strongly-typed React i18n Library based on simstate.