It appears that Bootstrap 4 has introduced a new method for updating the progress of your progress bar.
Aim: Dynamically update the progress bar percentage upon click
<div class="progress">
<div id='progressBar' class="progress-bar" role="progressbar" style="width: 25%;" aria-valuenow="25" aria-valuemax="100"></div>
</div>
My Approach to Updating the Percentage:
$( ".nextStep" ).click(function() {
$( "#progressBar" ).css({"width": "90%"});
});