hook-blog-counter-class.js

import React, { Component } from 'react'

export default class Counter extends Component {
  constructor(props) {
    super(props);
    this.state = {
      counter: 0
    }
    this.handleCounter = this.handleCounter.bind(this);
  }
  handleCounter(value) {
    this.setState({
      counter: value
    });
  }
  render() {
    return (
      <div>
        <div>
          <button onClick={() => this.handleCounter(this.state.counter + 1)}> + Increment</button>
          <button onClick={() => this.handleCounter(this.state.counter - 1)}> - Decrement</button>
        </div>
        <div>
          Current: {this.state.counter}
        </div>
      </div>
    )
  }
}

It is recommended to use prevState in setState instead of this.state inside render method.

Also there is no need for a handleCounter method if you already use a lambda - you could just directly call setState and make the code a lot smaller - this example really is a bad one for comparing classes to hooks >_<