how to setstate in class component react code example

Example 1: this setstate previous state react

state = {count: 0}

increment = () => { 
this.setState(previousState => ({
count: previousState.count + 1
}))
}

Example 2: react lifecycle example

class Test extends React.Component {
  constructor() {
    console.log('Constructor')
    super();
    this.state = {
      count: 0
    };
  }

  componentDidMount() {
    console.log("component did mount");
  }
  componentDidUpdate() {
    console.log("component did update");
  }

  onClick = () => {
    this.setState({ count: this.state.count + 1 });
  };
  render() {
    console.log("render");
    return (
      

        Hello Test
        
      		{this.state.count}
		
      
    );
  }
}


//--for first time
//Constructor
//render
//component did mount
//--for any update
//render
//component did update

Example 3: setstate in react

Functional Component
const [counter, setCounter] = useState(0);

setCouter(counter + 1);

Example 4: 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}
        
      
    )
  }
}