Adding Tether

Tether is a JavaScript library for efficiently making an absolutely positioned element stay next to another element on the page. For example, you might want a tooltip or dialog to open and remain next to the relevant item on the page.

In Bootstrap 4, Tether is integrated into tooltips and popovers for better auto-placement and performance. So, to make tooltips and popovers work in Bootstrap 4, you have to enqueue tether.js.

Add this line of code to the top of the bootstrap.min.js file to enqueue tether from a CDN:

<script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.2.0/js/tether.min.js"></script>