button click

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

import "./styles.css";

class App extends React.Component {
  render() {
    return (
      <div>
        <Counter />
        <Counter />
        <Counter />
      </div>
    );
  }
}

class Header extends React.Component {
  render() {
    return (
      <div>
        <h1>{this.props.name}</h1>
      </div>
    );
  }
}
// props -> properties

class Counter extends React.Component {
  state = {
    angka: 0
  };
  naik = () => {
    this.setState({
      angka: this.state.angka + 1
    });
  };

  turun = () => {
    this.setState({
      angka: this.state.angka - 1
    });
  };

  render() {
    return (
      <div>
        <h1>{this.state.angka}</h1>
        <button onClick={this.naik}>+</button>
        <button onClick={this.turun}>-</button>
      </div>
    );
  }
}
const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);