class-counter.js

import React, { Component } from 'react';

class Counter extends Component {
  constructor() {
    super();
    this.state = {
      count: 1
    };
  }

  handleClick = () => {
    this.setState(prevState => ({count: prevState.count + 1}))
  }

  render() {
    const { count } = this.state;
    return (
      <div>
        <h3 className="center">
            Welcome to the Counter of Life 
        </h3>
        <button className="center-block" onClick={this.handleClick}>
            {count}
        </button>
      </div>
    );
  }
}