I have an external website that is pretty much a form that interfaces with another enterprise software. One of the requirements of the fields in the form is to provide a location. We have the list of locations in our SharePoint, so I want to reference the SharePoint locations in a cascading drop down list on our form.

I am pretty new to referencing SharePoint-related services to external websites, and could really use a jumpstart. I've tried YouTube searching video demonstrations and reading some articles, but could not find my solution. I'm using predominantly HTML/CSS/JS/JQUERY for our external website.

Thank you so much!