The render method

render.js

class App extends Component {
    // All previous methods ...

    render() {
        const { boardStatus, isGameRunning, generation, speed } = this.state;

        return (
            <div>
                <h1>Game of Life</h1>
                <BoardGrid boardStatus={boardStatus} onToggleCellStatus={this.handleToggleCellStatus} />
                <div className='flexRow upperControls'
                    <span>
                        {'+ '}
                        <Slider speed={speed} onSpeedChange={this.handleSpeedChange} />
                        {' -'}
                    </span>
                    {`Generation: ${generation}`}
                </div>
                <div className='flexRow lowerControls'>
                    {this.runStopButton()}
                    <button type='button' disabled={isGameRunning} onClick={this.handleStep}>Step</button>
                    <button type='button' onClick={this.handleClearBoard}>Clear Board</button>
                    <button type='button' onClick={this.handleNewBoard}>New Board</button>
                </div>
            </div>
        );
    }
}