import React, {useState, useEffect} from 'react';
import ReactDOM from 'react-dom';
import randomColor from 'randomcolor'

function Counter(props) {
  const [count, setCount] = useState(0)
  useEffect(() => {
    // should run on mount
    document.body.style.background = randomColor()
  })
  return (
    <div>
      <button onClick={() => setCount(state => state + 1)}>👍</button>
      <h1>{count}</h1>
    </div>
  )
}

ReactDOM.render(<Counter />, document.getElementById('root'));