Do you want to quickly learn a new programming language while still having a fairly good knowledge of another, such as Ruby?
After reading the official documentation and the book recommended by the community, I would advise you look at comparison lists of how something can be done in a language that you know and how it is done in another language that you are trying to learn.

#Polyglot #Learning #JavaScript #Ruby #Python #PHP #Perl #Java #Go #Rust

These two resources provide a great foundation:
* https://hyperpolyglot.org/scripting
* https://www.lurklurk.org/rosetta.html

Even if the new language isn't on these sites, you can follow their plan. It will even be more effective than just watching this sites.

Scripting Languages I: Node.js, Python, PHP, Ruby - Hyperpolyglot