React Clicker

click.js

import React, { Component } from 'react'

class App extends Component {
  constructor () {
    super() // allows us to use `this`

    this.state = {
      count: 10
    }
  }

  /*
  increment = () => {} // preserves `this` from Component state
  increment () {} // `this` refers to the state of the function and not the React Component
  */
  increment = () => {
    /* 
    create a 'pure copy' of the state instead of altering the current state
    so, no `this.state.count++`, do `this.setState ({ count: this.state.count + 1})` instead
    */
    this.setState ({
      count: this.state.count + 1
    }) 
  }
  render () {
    return (
      <div>
        <button onClick={this.increment}>Increment</button>
        {this.state.count}
      </div>
    )
  }
}

export default App;