Quote Generator AJAX & API issues - Vanilla JS

Hello!

I’m attempting to create a random quote generator using only vanilla JS and this api

https://api.forismatic.com/api/1.0/?method=getQuote&format=json&lang=en

I’m having a hard time wrapping my head about a vanilla JS api call and AJAX. I’ve successfully made a quote generator with jQuery, but I can’t seem to get the vanilla js AJAX call to work, does anyone have any resources or examples of an AJAX call in vanilla JS?

My code is here if anyone is interested.
https://codepen.io/runsf/details/qVXXoV/