Don't know what the difference between stateful and stateless is, or what higher order functions are? On the auth0.com site Sebastián Peyrott explains these terms and other modern JavaScript concepts.

Modern JavaScript has experienced massive proliferation over recent years and shows no signs of slowing. Numerous concepts appearing in JS blogs and documentation are still unfamiliar to many front-end developers. In this post series, we'll learn intermediate and advanced concepts in the current front-end programming landscape and explore how they apply to modern JavaScript.

https://auth0.com/blog/glossary-of-modern-javascript-concepts/