Understand a style of JavaScript programming present in for example '...building a role playing game"

For context I am Math graduate with Matlab as my general purpose programming first language. I learned a obscure one called Mosel (could also call it FICO Xpress) at the same time. I found Python easy to pick up.
I am sometimes finding JavaScript difficult to get my head around or put a different way think in for example in “Learn basic JavaScript by building a role playing game.” For clarity I have completed that program I just want to be more in my element next time. This probably as this is program using an object oriented style but correct me if I am wrong? I know it is complicated when it comes the object orientated and JavaScript but maybe not understand super well.
I have more to say but I will wait to find out if this program is object orientated and maybe if not what it is. I suggest you answer this question and wait for me to give more context before giving a more detailed response.

while it uses objects, it doesn’t use OOP. OOP in JavaScript would use classes, and method on those classes.

there isn’t a specific style like OOP or functional programming used for the project

if you are finding javascript difficult with this curriculum, try to follow the Full Stack curriculum

I will consider checking out that course depend on how I am feeling after a few more lessons. I will not mark this as a solution as yet as feel others may have something more to add.
Changing the subject, I understand it is a matter of debate whether you can programme in an object orientated way in JavaScript you hold one view maybe the majority opinion.