doc.js

export default () => {
  // BEGIN (write your solution here)
  const makeActive = (element) => {
    const link = element.getAttribute('href').substr(1);
    const currentTab = element.parentNode.parentNode.getElementsByClassName('nav-link active')[0];
    const currentLink = currentTab.getAttribute('href').substr(1);
    const currentDiv = document.getElementById(link);
    const findDiv = document.getElementById(link);
    currentDiv.setAttribute('class', 'tab-pane');
    findDiv.setAttribute('class', 'tab-pane active');
    element.setAttribute('class', 'nav-link active');
    currentTab.setAttribute('class', 'nav-link');
    return;
  };
  const nav = document.querySelectorAll('a[data-toggle]');
  nav.forEach(node => {
    node.addEventListener('click', makeActive(node));
  });
  // END
};