Counter.js

import React from 'react'
import { Provider } from './context'

class Counter extends React.Component {

  constructor (props) {
    super(props)
    this.state = {
      counter: {
        value: 0,
        inc: this.inc,
        dec: this.dec
      }
    }
  }

  inc = () => {
    this.setState(({counter})=>({
      counter: {
      	...counter,
      	value: counter.value+1
      }
    }))
  } 

  dec = () => {
    this.setState(({counter})=>({
      counter: {
      	...counter,
      	value: counter.value-1
      }
    }))
  }
  
  render () {
    return (
      <Provider value={this.state.counter}>
        <CounterCard/>
      </Provider>
    )
  }

}

export default Counter