реагировать условное имя класса
<div className={`banner ${active ? "active" : ""}`}>{children}</div>
Gorgeous Goosander
<div className={`banner ${active ? "active" : ""}`}>{children}</div><span className={todo.completed ? "true" : ""}><div className={`btn-group pull-right ${this.props.showBulkActions ? 'shown' : 'hidden'}`}>
<div className={"btn-group pull-right " + (this.props.showBulkActions ? 'show' : 'hidden')}>