.jsx

import BonusContext from './bonus-context';

class App extends Component {
  static contextType = BonusContext;

  render() {
    return(
    <li className={ this.context ? 'current' : '' }>
      <NavLink
         exact
         to="/bonuses"
         data-hover="Alla Bonusar">
         Alla Bonusar
       </NavLink>
     </li>
     );
   }
 }






Child component  Bonuses.js
#########################

const BonusContext = React.createContext(true);
class Bonuses extends Component {  
...

bonus-context.js

export const BonusContext = React.createContext({
  bonus: false
  toggleBonus: () => this.bonus = !this.bonus
});