ReactN is a extension of React that includes global state management.
npm install reactn --save
oryarn add reactn
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')
);
For functional 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 functional 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 from which you want to read and to which you want
write.
You may alternatively use [ global, setGlobal ] = useGlobal()
to access the
entire global object.
Global state in class components behaves exactly like local state! Instead of
this.state
and this.setState
to read and write to the local state, you can
use this.global
and this.setGlobal
to read from and write to the global
state object.
If you prefer Redux's connect
functionality, pure functions, or are dealing
with deeply nested objects, a withGlobal
higher-order component is also
available.
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(
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 'reactn';
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(
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 React v16.7 alpha, 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;
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); // undefined
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
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);