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I'm trying to get super comfortable with the modern JavaScript and hence I built this app using Classes, which are an inevitable part of OOP. Take a look and tell me what could be improved. Appreciate any type of criticism.

Hello This is my first ever submission on the site. I'm not a newbie to coding web pages but I'm not confident enough as to whether I'm following the best practices or not. So I hope to get a review of what are the mistakes I made, what could be the best approaches and where from I could learn those things.