title: How to install popper.js with Bootstrap 4?
body: <p>From what I've read so far, popper.js is a big pain with Bootstrap 4. I can't get it to work. I keep getting this error:</p>
  
  <blockquote>
    <p>Error: Bootstrap dropdown require Popper.js (<a href="https://popper.js.org" rel="noreferrer">https://popper.js.org</a>)</p>
  </blockquote>
  
  <p>I've tried the CDN and NPM install. Same result. At the bottom of my HTML file, I have this for the NPM install:</p>
  
  <pre><code>&lt;script src="js/jquery.min.js"&gt;&lt;/script&gt;
  &lt;script src="js/popper.min.js"&gt;&lt;/script&gt;
  &lt;script src="js/tether.min.js"&gt;&lt;/script&gt;
  &lt;script src="js/bootstrap.min.js"&gt;&lt;/script&gt;
  </code></pre>
  
  <p>Then tried this for the CDN:</p>
  
  <pre><code>&lt;script src="/js/jquery.min.js"&gt;&lt;/script&gt;
  &lt;script src="/js/tether.min.js"&gt;&lt;/script&gt;
  &lt;script src="https://cdnjs.com/libraries/popper.js"&gt;&lt;/script&gt;
  &lt;script src="/js/bootstrap.min.js"&gt;&lt;/script&gt;
  </code></pre>
  
  <p>Any ideas what I'm doing wrong?</p>