Toggle.js

export default class Toggle extends Component {
    state = { on: false }

    onClick = (e) => {
        e.preventDefault();

        this.setState(state => ({
            on: !state.on,
        }));
    }

    render() {
        const { on } = this.state;

        return this.props.children({
            on,
            onToggle: this.onClick,
        });
    }
}