[ ReactJs ] create "ON OFF" toggle button (https://codesandbox.io/s/toggle-yzxy2)

Toggle.js

import React from "react";

class App extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      isToggleOn: true,
      isToggleAdd: true
    };
  }

  handleClickOn = () => {
    this.setState(prevState => ({
      isToggleOn: !prevState.isToggleOn
    }));
  };

  handleClickAdd = () => {
    this.setState(prevState => ({
      isToggleAdd: !prevState.isToggleAdd
    }));
  };

  render() {
    return (
      <div>
        <button onClick={this.handleClickOn}>
          {this.state.isToggleOn ? "ON" : "OFF"}
        </button>
        <br />
        <br />
        <button onClick={this.handleClickAdd}>
          {this.state.isToggleAdd ? "ADD" : "REMOVE"}
        </button>
      </div>
    );
  }
}

export default App;