jQuery addClass example

Change class name on click in jQuery

HTML

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.3.1/css/bootstrap.min.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.3.1/js/bootstrap.bundle.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.1/jquery-ui.min.js"></script>
<i class="fas fa-question-circle" rel="tooltip" data-placement="right" data-original-title="My tooltip"></i>

CSS

.fa-question-circle:before {
    content: "\f059";
}

JavaScript

$("[rel=tooltip]").tooltip({html:true});