use-global-hook

Painless global state management for React using Hooks and Context API in 1KB!

Installation

npm install @devhammed/use-global-hook

Quick Example

import React from 'react'
import ReactDOM from 'react-dom'
import { GlobalHooksProvider, createGlobalHook, useGlobalHook } from '@devhammed/use-global-hook'

const store = createGlobalHook(/** 1 **/ 'counterStore', () => {
  const [count, setCount] = React.useState(0)

  const increment = () => setCount(count + 1)
  const decrement = () => setCount(count - 1)
  const reset = () => setCount(0)

  return { count, increment, decrement, reset }
})

function Counter () {
  const { count, increment, decrement, reset } = useGlobalHook('counterStore') /** 1. This is where you use the name you defined in `createGlobalHook` function, this name should be unique through out your app **/

  return (
    <div>
      <button onClick={decrement}>-</button>
      <span>{count}</span>
      <button onClick={increment}>+</button>
      <button onClick={reset}>reset</button>
    </div>
  )
}

function App () {
  return (
    <GlobalHooksProvider hooks={[ store ]}>
      <Counter />
      <Counter />
      <Counter />
    </GlobalHooksProvider>
  )
}

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

Notice how we render the Counter component three times? clicking on a button in one of the component instance will update others too.

See it running live here.

Concepts

use-global-hook is built on top of React Hooks and Context API. I first used this concept in a project at my workplace Epower and seeing the re-usability and convenience, I decided to convert it to a standalone open-source library for others to benefit from the awesomeness of React Hooks.

Store

A hook store is a place to store state and some of the logic for updating it.

Store is a very simple React hook wrapper (which means you can re-use it, use other hooks within it, etc).

createGlobalHook is a Hook store function wrapper, this function is used to apply some internally used property to a function that calls your original hook function. A wrapper function is best for this case as it is not a good practice to mutate your original function with properties that may conflict and third-party hooks is taking into consideration where it is not good to add properties to the library core exports and this method also allows creating clone of same hook function without conflicting instances.

Wrapping the function means, in case of when creating dynamic hook function, any argument you intend to pass to your hook when will be applied automatically, you still have your function the way you declare it and the way you intend to use it --- cheers! e.g something like store(props.dynamicValue) though this can only happen when registering the hook function in <GlobalHooksProvider />.

import React from 'React'
import { createGlobalHook } from '@devhammed/use-global-hook'

const store = createGlobalHook('counterStore', () => {
  const [count, setCount] = React.useState(0)

  const increment = () => setCount(count + 1)
  const decrement = () => setCount(count - 1)
  const reset = () => setCount(0)

  return { count, increment, decrement, reset }
})

This example uses the official React useState() hook, but you are not limited to this only, there are other hooks like useReducer() if you need something like Redux or any custom or third-party hook as far as it follows the Rules of Hooks, you can read more on Hooks on React official website here.

useGlobalHook

Next we'll need a piece to introduce our state back into the tree so that:

• When state changes, our components re-render.
• We can depend on our store state.
• We can call functions exposed by the store.

For this we have the useGlobalHook hook which allows us to get global store instances by using passing the value we used when creating the global hook with createGlobalHook function.

function Counter () {
  const { count, decrement, increment } = useGlobalHook('counterStore')

  return (
    <div>
      <span>{count}</span>
      <button onClick={decrement}>-</button>
      <button onClick={increment}>+</button>
    </div>
  )
}

<GlobalHooksProvider>

The <div> component has two roles:

1. It initializes global instances of given hooks array (an Array is required because React expects the number of hooks to be consistent across re-renders and Objects are not guaranteed to return in same order)
2. It uses context to pass initialized instances of given stores to all the components down the tree.

ReactDOM.render(
  <GlobalHooksProvider hooks={[ counterStore ]}>
    <Counter />
  </GlobalHooksProvider>
);

Nesting Providers

use-global-hook supports nesting GlobalHooksProvider which means child components can have their own global state and still be able to access their parent or root global state. Take a look at below example, explanation comes after it.

  import React from 'react'
  import ReactDOM from 'react-dom'
  import {
    GlobalHooksProvider,
    useGlobalHook,
    createGlobalHook
  } from '@devhammed/use-global-hook'

  const counterStoreHook = createGlobalHook('counterStore', () => {
    const [count, setCount] = React.useState(0)

    const increment = () => setCount(count + 1)
    const decrement = () => setCount(count - 1)
    const reset = () => setCount(0)

    return { count, increment, decrement, reset }
  })

  const timerHook = createGlobalHook('timerStore', () => {
    const [time, setTime] = React.useState(new Date())

    React.useEffect(() => {
      const id = setInterval(() => setTime(new Date()), 1000)
      return () => clearInterval(id)
    }, [])

    return time
  })

  function Time () {
    const time = useGlobalHook('timerStore')
    const { count } = useGlobalHook('counterStore')

    return <p>{time.toString()} - {count}</p>
  }

  function Timer () {
    return (
      <GlobalHooksProvider hooks={[ timerHook ]}>
        <Time />
        <Time />
        <Time />
      </GlobalHooksProvider>
    )
  }

  function Counter () {
    const { count, increment, decrement, reset } = useGlobalHook('counterStore')

    return (
      <div>
        <button onClick={decrement}>-</button>
        <span>{count}</span>
        <button onClick={increment}>+</button>
        <button onClick={reset}>reset</button>
      </div>
    )
  }

  function App () {
    return (
      <GlobalHooksProvider hooks={[ counterStoreHook ]}>
        <Timer />
        <Counter />
        <Counter />
        <Counter />
      </GlobalHooksProvider>
    )
  }

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

View Demo

See how the Time components wrapped by Timer are able to access both counterStore and timerStore? When you render GlobalHooksProvider, one of the things it does under the hood is to try to use it parent global context, If it is undefined this means that it is the root else it merges with the parent context and you are able to access any store hook from parent(s) but the parent cannot access child nested global state because data flows in one direction else you define a function in global state that will communicate to other component.

Class Components

You heard that right, who says class component cannot use and benefit from the awesomeness of React hooks? use-global-hooks provides a function component HOC wrapper withGlobalHooks which allows class components to use hooks state(s) by passing them props. cool right? let's look at how above Counter component will look when using a class.

  // Counter.js

  import { withGlobalHooks } from '@devhammed/use-global-hook'

  class Counter extends React.Component {
    render () {
      const { count, increment, decrement, reset } = this.props.counterStore

      return (
        <div>
          <button onClick={decrement}>-</button>
          <span>{count}</span>
          <button onClick={increment}>+</button>
          <button onClick={reset}>reset</button>
        </div>
      )
    }
  }

  export default withGlobalHooks(Counter, ['counterStore'])

It is as easy as using function component too, just pass in your component variable as the first parameter and second parameter is an array that contains names of the global hooks you want to use and you will be able access the state from this.props.[globalHookName]. The HOC wrapper pass down props so any other prop you are using in your component still works fine except if there is prop conflict which is why it is recommended you add Store suffix to your store names when creating them.

So with support for class component, you can start using this library even when you are not ready to switch to function components.

NOTE: You can also use withGlobalHooks with function components but why not just use the hook? 😉

Testing

Global Hooks are just your regular hooks too, so you can easily test with react-hooks-testing-library library e.g

import { renderHook, act } from 'react-hooks-testing-library'

test('counter', async () => {
  let count, increment, decrement
  renderHook(() => ({count, increment, decrement} = counterStore()))

  expect(count).toBe(0)

  act(() => increment())
  expect(count).toBe(1)

  act(() => decrement())
  expect(count).toBe(0)
})