class components and state code example

Example 1: 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 (
      <div>
        Hello Test
        <button onClick={this.onClick}>
      		{this.state.count}
		</button>
      </div>
    );
  }
}


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

Example 2: setstate react js

constructor(props) {
        super(props);
        this.state = {
            isActive: true,
        };
    }

    checkStatus = () => {
        this.setState({		// use this function
            'isActive' : !this.state.isActive,
        });
    }

Example 3: reactjs update state example

{
  hasBeenClicked: false,
  currentTheme: 'blue',
}