react update components on state update code example

Example 1: set state

class App extends React.Component {

state = { count: 0 }

handleIncrement = () => {
  this.setState({ count: this.state.count + 1 })
}

handleDecrement = () => {
  this.setState({ count: this.state.count - 1 })
}
  render() {
    return (
      

        

          {this.state.count}
        
        Increment by 1
        Decrement by 1
      
    )
  }
}

Example 2: react lifecycle hooks

class ActivityItem extends React.Component {
  render() {
    const { activity } = this.props;

    return (
      

        

          
        

        
          {moment(activity.created_at).fromNow()}
        
        
        
{activity.actor.display_login} {activity.payload.action}
        

          {activity.repo.name}
        
      
    )
  }
}