ReactN is a extension of React that includes global state management.
npm install reactn --saveoryarn add reactn
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!
Global state in function components behaves almost identically to local state.
Instead of [ value, setValue ] = useState(defaultValue), you can use
[ value, setValue ] = useGlobal(property) where property is the property of
the global state you want to get and set.
You may also use [ global, setGlobal ] = useGlobal() to access the entire
global object.
You may also use [ state, dispatch ] = useGlobal(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.
Global state in class components behaves exactly like local state! Instead of
this.state and this.setState to get and set the local state, you can use
this.global and this.setGlobal to get and set the global state.
Alternatively, the @reactn decorator allows you to convert classes that
extend React.Component to ReactN global state components.
If you prefer Redux's connect functionality, pure functions, or are dealing
with deeply nested objects, a
withGlobal higher-order component is also an available option.
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.
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, the same way a Redux store would be initialized this way.
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')
);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 member variable 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>
);
}
}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>
);
}
}Using React Hooks in version 16.8
(or above), 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 useGlobal hook analogously to the useReducer hook by
providing a function to useGlobal.
import React, { useGlobal } from 'reactn'; // <-- reactn
const incrementReducer = (global, action) => ({
count: global.count + action.amount
});
const decrementReducer = (global, action) => ({
count: global.count - action.amount
});
const MyComponent = () => {
// In most cases, you only want the dispatch function and not a copy of the
// global state.
const dispatch1 = useGlobal(incrementReducer);
// You may use [ state, dispatch ] to match useReducer, where state is the
// global state.
const [ state, dispatch2 ] = useGlobal(decrementReducer);
return (
<div>
<button onClick={() => dispatch1({ amount: 1 })}>Add 1</button>
<button onClick={() => dispatch1({ amount: 3 })}>Add 3</button>
<button onClick={() => dispatch2({ amount: 5 })}>Subtract 5</button>
</div>
);
};
export default MyComponent;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 });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.global.reducerName or useGlobal('reducerName').
The second parameter is the reducer function. The reducer function that you write has two parameters: first, the global state; second, the value passed to the reducer. The reducer function that you use has one parameter: the value to pass to the reducer.
import { addReducer, setGlobal, 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, x = 1) => ({
value: global.value + x
}));
function MyComponent() {
const increment = useGlobal('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.global.increment(value).
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 insure 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;
}
}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 });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); // undefinedUse setGlobal to initialize or update your global state. This is analogous to
calling this.setGlobal in a class component or useGlobal()[1] in a
functional 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);
}
);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);