ysm-dev / reactn

React, but with built-in global state management.

ReactN

ReactN is a extension of React that includes global state management. It treats global state as if it were built into React itself -- without the boilerplate of third party libraries.

For support, reach out to us on the Reactiflux Discord channel #reactn.

Install

• npm install reactn or
• yarn add reactn

Features

No Boilerplate!

For function components, import { useGlobal } from 'reactn'; to harness the power of React Hooks!

For class components, simply change import React from 'react'; to import React from 'reactn';, and your React class components will have global state built in!

If you prefer class decorators, you can continue to import React from 'react'; for your components and additionally import reactn from 'reactn'; for access to the @reactn decorator!

Intuitive!

Function Components

Global state in function components behaves almost identically to local state.

You use [ global, setGlobal ] = useGlobal() to access the entire global state object.

You use [ value, setValue ] = useGlobal(property) where property is the property of the global state you want to get and set.

Global reducers in function components behaves almost identically to local reducers.

You use dispatch = useDispatch(reducerFunction) to mimic the behavior of useReducer, where instead of providing an initial state, the state of the reducer is the ReactN global state object.

You use dispatch = useDispatch(reducerName) to use a reducer that was added by the addReducer helper function.

Class Components

Global state in class components behaves exactly like local state!

You use this.global and this.setGlobal to get and set the global state.

You use this.dispatch.reducerName() to dispatch to a reducer that was added by the addReducer helper function.

The @reactn decorator allows you to convert classes that extend React.Component to ReactN global state components.

Map State to Props

If you prefer Redux's connect functionality, pure functions, or are dealing with deeply nested objects, a withGlobal higher-order component is also available.

Table of Contents

• Install
• Features
  • No Boilerplate!
  • Intuitive!
• Getting Started
  • Managing Multiple States
  • Initializing Your State
  • Examples
    • Class Components
    • Class Components (with Decorator)
    • Function Components
    • Helper Functions
      • addCallback
      • addReducer
      • getDispatch
      • getGlobal
      • removeCallback
      • resetGlobal
      • setGlobal
• Frequently Asked Questions
• Support

Getting Started

Managing Multiple States

This README is for managing a single global state. This is ideal for most applications. If you are using concurrent server-side rendering or otherwise want to work with multiple global states, follow the README for the Provider component, which allows you to limit a ReactN state to a React Context.

If you are unsure whether or not you need multiple global states, then you do not need multiple global states.

Initializing Your State

You can initialize your global state using the setGlobal helper function. In most cases, you do not want to initialize your global state in a component lifecycle method, as the global state should exist before your components attempt to render.

It is recommended that you initialize the global state just prior to mounting with ReactDOM.

import React, { setGlobal } from 'reactn';
import ReactDOM from 'react-dom';
import App from './App';

// Set an initial global state directly:
setGlobal({
  cards: [],
  disabled: false,
  initial: 'values',
  x: 1,
});

ReactDOM.render(
  <App />,
  document.getElementById('root')
);

Examples

Class Components

By importing React from reactn instead of react, you bake global state directly into the React namespace. As a result, Component and PureComponent will have access to the global and dispatch member variables and setGlobal method.

import React from 'reactn'; // <-- reactn
import Card from '../card/card';

// Render all cards in the global state.
export default class Cards extends React.PureComponent {

  componentDidMount() {

    // Hydrate the global state with the response from /api/cards.
    this.setGlobal(

      // Despite fetch returning a Promise, ReactN can handle it.
      fetch('/api/cards')
        .then(response => response.json())

        // Set the global `cards` property to the response.
        .then(cards => ({ cards }))

        // Fail gracefully, set the global `error`
        //   property to the caught error.
        .catch(err => ({ error: err }))
    );
  }

  render() {

    // For each card in the global state, render a Card component.
    // this.global returns the global state,
    //   much the same way this.state returns the local state.
    return (
      <div>
        {this.global.cards.map(card =>
          <Card
            key={card.id}
            {...card}
          />
        )}
      </div>
    );
  }
}

Class Components (with Decorator)

By importing React and ReactN separately, the React namespace remains unchanged. You can inject ReactN's global functionality into your vanilla React component by using the @reactn decorator imported from the reactn package.

import React from 'react';
import reactn from 'reactn'; // <-- reactn
import Card from '../card/card';

// Render all cards in the global state.
@reactn
export default class Cards extends React.PureComponent {

  componentDidMount() {

    // Hydrate the global state with the response from /api/cards.
    this.setGlobal(

      // Despite fetch returning a Promise, ReactN can handle it.
      fetch('/api/cards')
        .then(response => response.json())

        // Set the global `cards` property to the response.
        .then(cards => ({ cards }))

        // Fail gracefully, set the global `error`
        //   property to the caught error.
        .catch(err => ({ error: err }))
    );
  }

  render() {

    // For each card in the global state, render a Card component.
    // this.global returns the global state,
    //   much the same way this.state returns the local state.
    return (
      <div>
        {this.global.cards.map(card =>
          <Card
            key={card.id}
            {...card}
          />
        )}
      </div>
    );
  }
}

Function Components

Using React Hooks, you can harness useGlobal to access the global state.

import React, { useGlobal } from 'reactn'; // <-- reactn
import Card from '../card/card';

// Render all cards in the global state.
const Cards = () => {

  // Use the hook to get all cards in the global state.
  //   setCards is not used in this example.
  const [ cards, setCards ] = useGlobal('cards');

  // For each card in the global state, render a Card component.
  return (
    <div>
      {cards.map(card =>
        <Card
          key={card.id}
          {...card}
        />
      )}
    </div>
  );
};

export default Cards;

You may also use the useDispatch hook analogously to the useReducer hook by providing a function to useDispatch.

import React, { useDispatch } from 'reactn'; // <-- reactn

const incrementReducer = (global, action) => ({
  count: global.count + action.amount,
});

const decrementReducer = (global, action) => ({
  count: global.count - action.amount,
});

const MyComponent = () => {
  const increment = useDispatch(incrementReducer);
  const decrement = useDispatch(decrementReducer);

  return (
    <div>
      <button onClick={() => increment({ amount: 1 })}>Add 1</button>
      <button onClick={() => increment({ amount: 3 })}>Add 3</button>
      <button onClick={() => decrement({ amount: 5 })}>Subtract 5</button>
    </div>
  );
};

export default MyComponent;

Helper Functions

addCallback

Use addCallback to execute a function whenever the state changes. The return value of the callback will update the global state, so be sure to only return undefined or null if you do not want the global state to change. Be aware that always returning a new state value will result in an infinite loop, as the new global state will trigger the very same callback.

The only parameter is the callback function.

import { addCallback, setGlobal } from 'reactn';

// Every time the global state changes, this function will execute.
addCallback(global => {
  alert(`The new value is ${global.value}!`);

  // If the global state was changed to 1, change it to 2.
  if (global.value === 1) {
    return { value: 2 };
  }

  // If the global state is anything other than 1, don't change it.
  return null;
});

setGlobal({ value: 1 });
// The new value is 1!
// The new value is 2!

The return value of addCallback is a function that, when executed, removes the callback.

import { addCallback, setGlobal } from 'reactn';

const removeAlert = addCallback(global => {
  alert(global.value);
});

// The callback causes an alert on global state change:
setGlobal({ value: 1 }); // 1
setGlobal({ value: 2 }); // 2

// No longer execute the callback.
removeAlert();

// No alerts:
setGlobal({ value: 3 });
setGlobal({ value: 4 });

addReducer

Use addReducer to add a reducer to your global state.

The first parameter is the name of your reducer. You will access your reducer by this name. this.dispatch.reducerName or useDispatch('reducerName').

The second parameter is the reducer function. The reducer function that you write has at least two parameters: first, the global state; second, a map of your reducers. The third and onward parameters are the arguments that you pass when dispatching. The reducer function that you use when dispatching does not contain the global state or map of reducers. Those are prefixed for you automatically.

import { addReducer, setGlobal, useDispatch, useGlobal } from 'reactn';

// Initialize the global state with the value 0.
setGlobal({ value: 0 });

// When the increment reducer is called, increment the global value by X.
addReducer('increment', (global, dispatch, x = 1) => ({
  value: global.value + x
}));

function MyComponent() {
  const increment = useDispatch('increment');
  const [ value ] = useGlobal('value');
  return (
    <>
      The value is{' '}
      <button
        onClick={() => {

          // Increment from 0 to 1.
          // (the default value of the reducer is 1)
          if (value === 0) {
            increment();
          }

          // Increment from 1 to 5.
          else if (value === 1) {
            increment(4);
          }
        }}
        value={value}
      />
    </>
  );
}

For a class component, the analogous method is this.dispatch.increment(value).

The dispatch parameter on a reducer allows you to write "sagas," or a single reducer that dispatches other reducers.

// add(1)
addReducer('add', (global, dispatch, i) => ({
  x: global.x + i,
}));

// subtract(2)
addReducer('subtract', (global, dispatch, i) => ({
  x: global.x - i,
}));

// addSubtract(1, 2)
addReducer('addSubtract', async (global, dispatch, i, j) => {
  await dispatch.add(i);
  await dispatch.subtract(j);
});

addReducers

addReducers accepts an object where the keys are reducer names and the values are reducers. addReducers is just a convenient shorthand for calling addReducer multiple times.

getDispatch

Use getDispatch to return an object of the global dispatch functions. You only want to use this in helper libraries, and not in Components. Components should use useDispatch or this.dispatch.

getDispatch has no parameters.

import { getDispatch } from 'reactn';

// Access this.dispatch.reducerName outside of a Component.
class HelperLibrary {
  getDispatcherFunction() {
    return getDispatch().reducerName;
  }
}

getGlobal

Use getGlobal to return a current snapshot of the global state. You only want to use this in helper libraries, and not in Components. Components should use useGlobal or this.global to ensure that they re-render when the global state changes. getGlobal will not cause a Component reliant on the global state to re-render, nor will it cause a library function to re-execute. It does nothing more than return a current snapshot of the global state.

getGlobal has no parameters.

import { getGlobal } from 'reactn';

// Access this.global.value outside of a Component.
class HelperLibrary {
  getGlobalValue() {
    return getGlobal().value;
  }
}

removeCallback

Use removeCallback to remove a callback that was added via addCallback. The callback must be the same function reference. This is equivalent to executing the return value of addCallback.

The only parameter is the callback function itself.

import { addCallback, removeCallback, setGlobal } from 'reactn';

function alertCallback(global) {
  alert(global.value);
}

addCallback(alertCallback);

// Alerts the global state value:
setGlobal({ value: 1 }); // 1
setGlobal({ value: 2 }); // 2

// Remove the alert callback:
removeCallback(alertCallback);

// No alerts:
setGlobal({ value: 3 });
setGlobal({ value: 4 });

resetGlobal

Use resetGlobal to reset the global state. This resets all state values, including callbacks, property listeners, and reducers.

There are no parameters.

import { getGlobal, resetGlobal, setGlobal } from 'reactn';

// Set the value.
setGlobal({ value: 1 });

// Get the value.
alert(getGlobal().value); // 1

// Reset the global state.
resetGlobal();

// Get the value.
alert(getGlobal().value); // undefined

setGlobal

Use setGlobal to initialize or update your global state. This is analogous to calling this.setGlobal in a class component or useGlobal()[1] in a function component.

The first parameter is the new global state that you want to set.

The optional second parameter is a callback.

setGlobal with a new global state:

import { setGlobal } from 'reactn';

// Set loading to true.
setGlobal({
  loading: true
});

setGlobal with a new global state and a callback:

import { setGlobal } from 'reactn';

// Set loading to true.
setGlobal(
  {
    loading: true
  },

  // After it is set, assert that loading is true.
  global => {
    assert(global.loading === true);
  }
);

withGlobal

Use withGlobal to return a higher-order component to convert global state values into props. This is highly analogous to react-redux's connect function.

The first parameter is a function for getting global state values.

The second parameter is a function for setting global state values (similar to dispatch).

import React, { withGlobal } from 'reactn';

// A button that displays the value and, when clicked, increments it.
function MyComponent(props) {
  return (
    <>
      My value is{' '}
      <button
        onClick={props.incrementValue}
        value={props.value}
      />
    </>
  );
}

export default withGlobal(

  // Set the `value` prop equal to the global state's `value` property.
  global => ({
    value: global.value
  }),

  // Important Note: This is not the setGlobal helper function.
  // Set the `incrementValue` prop to a function that increments the global
  //   state's `value` property.
  setGlobal => ({
    incrementValue: () => {

      // Important Note: This is not the setGlobal helper function.
      // This is the parameter referenced 4 lines up.
      setGlobal(global => ({
        value: global.value + 1
      }));
    }
  })
)(MyComponent);

Support

For support, reach out to us on the Reactiflux Discord channel #reactn.