Hooks API

class_state.js

import React from "react";
import ReactDOM from "react-dom";

class Hello extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
     text: 'Hello, World!'
    };
  }
}

// OR

class Hello extends React.Component {
  this.state = {
    text: 'Hello, World!'
  };
}


const root = document.getElementById("root");

ReactDOM.render(<Hello />, root);

func_state.js

import React, { useState } from "react";
import ReactDOM from "react-dom";

function Hello() {
  const [text, setText] = useState('Hello, World!');
  
  return (
    <div>{text}</div>
  );
}


const root = document.getElementById("root");

ReactDOM.render(<Hello />, root);