Answers for "state in constructor react"

class component react using state

import React, {Component} from 'react';
import './App.css';
import IconBar from './components/icon-bar';
import Events from './components/events';

class App() extends Component {
  constructor(props) {
        super(props)
        this.state = {
            mode: null
        }
        this.updateMode = this.updateMode.bind(this);
    }

  updateMode = (newMode) => {

      this.setState({mode: newMode});
  }


  return (
    <div className="App">
      <h1 className="Title">ENAKS</h1>
      <IconBar onUpdateMode={this.updateMode}  mode={this.state.mode} />
      <Events />
  <div className="mainModeFrame"><p1>{this.state.mode}</p1></div>
    </div>
  );
}

export default App;
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State on React class Component

class Example extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      count: 0
    };
  }

  render() {
    return (
      <div>
        <p>You clicked {this.state.count} times</p>
        <button onClick={() => this.setState({ count: this.state.count + 1 })}>
          Click me
        </button>
      </div>
    );
  }
}

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

component did mmount

componentDidUpdate(prevProps, prevState, snapshot)