React

by Abdul Ahmad

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 MyComponent extends React.Component {
  state = {
    time: 0,
  };

  componentDidMount() {
    setInterval(() => {
      const { time } = this.state;
      this.setState({ time: time + 1 });
    }, 1000);
  }

  render() {
    const { time } = this.state;
    
    return (
      <h1> 
        This component has been mounted for: { time } seconds
      </h1>
    );
  }
}

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