React useContext

When you dont need a store (yet) you can just use useContext, this hook helps avoid prop drilling and components taking a dependency on props they dont use other than passing to children components.

The code below is based on telerik.com: How to Use Context API and the complete source code is at https://github.com/carlpaton/react-usecontext

  1. Create the GlobalContextProvider at /src/context/GlobalContextProvider.js which will create all your contexts and provide API’s to maintain the state.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
import React, { useState, createContext, useContext } from 'react';

const GlobalSpinnerContext = createContext();
const GlobalSpinnerActionsContext = createContext();

/* eslint-disable */
const useContextFactory = (name, context) => {
  return () => {
    const ctx = useContext(context);
    if (ctx === undefined) {
      throw new Error(
        `use${name}Context must be used withing a ${name}ContextProvider.`
      );
    }
    return ctx;
  };
};
/* eslint-enable */

// eslint-disable-next-line react-hooks/rules-of-hooks
export const useGlobalSpinnerContext = useContextFactory(
  'GlobalSpinnerContext',
  GlobalSpinnerContext
);
// eslint-disable-next-line react-hooks/rules-of-hooks
export const useGlobalSpinnerActionsContext = useContextFactory(
  'GlobalSpinnerActionsContext',
  GlobalSpinnerActionsContext
);

const GlobalContextProvider = (props) => {
  const [isGlobalSpinnerOn, setGlobalSpinner] = useState(false);

  return (
    <GlobalSpinnerContext.Provider value={isGlobalSpinnerOn}>
      <GlobalSpinnerActionsContext.Provider value={setGlobalSpinner}>
        {props.children}
      </GlobalSpinnerActionsContext.Provider>
    </GlobalSpinnerContext.Provider>
  );
};

export default GlobalContextProvider;
  1. Wrap your application
1
2
3
4
5
6
7
8
9
10
function App() {
  return (
    <GlobalSpinnerContextProvider>
      <div className="App">
        <GlobalSpinner />
        <RandomComments />
      </div>
    </GlobalSpinnerContextProvider>
  );
}
  1. Access the contexts
1
2
3
4
5
6
7
8
9
10
11
12
13
14
import React from 'react'
import './globalSpinner.css'
import {useGlobalSpinnerContext} from '../../context/GlobalSpinnerContext'

const GlobalSpinner = props => {
  const isGlobalSpinnerOn  = useGlobalSpinnerContext()
  return isGlobalSpinnerOn ? (
    <div className="global-spinner-overlay">
      <p>Loading...</p>
    </div>
  ) : null
}

export default GlobalSpinner
  1. Access the actions to change the state
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
import React, {useState, useEffect } from 'react'
import {useGlobalSpinnerActionsContext} from '../context/GlobalSpinnerContext'


const RandomComments = props => {
  const [comments, setComments] = useState([])
  const setGlobalSpinner = useGlobalSpinnerActionsContext()
  useEffect(() => {
    (async () => {
        setGlobalSpinner(true)
        const result = await fetch('https://jsonplaceholder.typicode.com/comments?l=2')
        const data = await result.json()
        setComments(data.slice(0, 3))
        setGlobalSpinner(false)
    })()
  }, [setGlobalSpinner])

  return (
    <div>
      {comments.map(comment => {
        const {name, body, id} = comment
        return (
          <div key={id}>
            <p style={{fontWeight: 'bold'}}>{name}</p>
            <p> {body}</p>
          </div>
        )
      })}
    </div>
  )
}

export default RandomComments

References