title: How to initialize Tooltips in Bootstrap 4 with pure JavaScript? No jQuery
body: <p>I'm somehow stuck with this code:</p>
  
  <pre><code>$(function () {
    $('[data-toggle="tooltip"]').tooltip()
  });
  </code></pre>
  
  <p>I'd like to change it to pure JavaScript. I'm not sure how to call the tooltip function, I already have some ideas like:</p>
  
  <pre><code>var tooltips = document.querySelectorAll("[data-toggle='tooltip']");
  for(var i = 0; i &lt; tooltips.length; i++){
     //this gives an error
     tooltips[i].tooltip();
  }
  </code></pre>
  
  <p>I'm able to get all the tooltips, but I cannot initialize them. If I write something like this:</p>
  
  <pre><code>$(tooltips[i]).tooltip();
  </code></pre>
  
  <p>Then it works, but I want to remove the jQuery dependency since this is the only jQuery section that I have. Any idea? I've been searching and I cannot find anything useful.</p>