React

by stephenkingsley

HTML

<div id="app"></div>

CSS

body {
  background: #20262E;
  padding: 20px;
  font-family: Helvetica;
}

#app {
  background: #fff;
  border-radius: 4px;
  padding: 20px;
  transition: all 0.2s;
}

li {
  margin: 8px 0;
}

h2 {
  font-weight: bold;
  margin-bottom: 15px;
}

.done {
  color: rgba(0, 0, 0, 0.3);
  text-decoration: line-through;
}

input {
  margin-right: 5px;
}

React

class JOKER extends React.PureComponent {
  constructor(props) {
    super(props);
    this.state = {
      count: props.count,
    }
  }

  componentWillReceiveProps(nextProps) {
    console.log('I am JOKER\'s componentWillReceiveProps--->');
    this.setState({ count: nextProps.count });
  }

  render() {
    console.log('I am JOKER\'s render--->');
    const { count } = this.state;
    return (
      <div>
        <p style={{ color: 'red' }}>JOKER: You clicked {count} times</p>
      </div>
    );
  }
}

class DC extends React.PureComponent {
  constructor() {
    super();
    this.state = {
      count: 0,
    };
  }

  render() {
    const { count } = this.state;
    return (
      <div>
        <button onClick={() => {
        	this.setState({ count: count + 1, });
          console.log('\n')
        }}>
          Click me
        </button>
        <p>You clicked {count} times</p>
        <JOKER count={count} />
      </div>
    );
  }
}

ReactDOM.render(<DC />, document.querySelector("#app"))