title: How to remove all classes except the one you clicked?
body: <p>This functions starts when I click on a link. It needs to remove all '.is-active' classes on the elements with the attribute [data-route]. And add the class '.is-active' on the [data-route] element that is connected with the link I clicked on.</p>
  
  <pre><code>    toggle: function(section){
          var sections = document.querySelectorAll('[data-route]');
          for (i = 0; i &lt; sections.length; i++){
              document.querySelector('[data-route]').classList.remove('is-active');
          }
          document.querySelector(section).classList.add('is-active');
      }
  </code></pre>
  
  <p>But this doesn't work. It doesn't remove the classes? </p>
  
  <p>See example: <a href="http://jordypouw.github.io/myFED2/deeltoets1/index.html" rel="nofollow">http://jordypouw.github.io/myFED2/deeltoets1/index.html</a></p>
  
  <p><strong>P.S. it has to be in vanilla JavaScript.</strong></p>