What books(articles) can you suggest for improving skills? I'm not an expert, but not newbie guy. I'd worked with it about 3 years, but still, want to learn something new.
P.S. I'm interested in both client- and server-side usage of JavaScript.
I have been working with JavaScript for couple of years now, but only got to fully understand how JavaScript works when I read "You don't know JS" series by Kyle Simpson. In there you will find detail explanation on scope, this binding, prototype, async JS, performance, types and ES6. Although I admit that Kyle has some thoughts on his own on some of JavaScript features, this series gave me ability to fully understand and work with JavaScript in any environment, client, server and hybrid. Can't recommend it more!
Ritwik Sahoo
To Code and Beyond
I started with basic Javascript from MDN and ended up with this superlist - superherojs.com.