The answer is never, or almost never. Certainly never more than one level.

Good to hear:

• Rarely, almost never, or never.
• A single level is sometimes OK, from a framework base-class such as React.Component.
• “Favor obje...

It produces programs by composing mathematical functions and avoids shared state & mutable data.

• Good to hear: Pure functions/function purity; Avoid side-effects; Simple function composition; Examples of functional languages: Lisp, ML, Haskell, Erlang,...

Good to hear:  

• An understanding of what blocking means, and the performance implications. 
• An understanding of event handling, and why its important for UI code. 

• Good to hear: Mentions of trouble with shared state, different things competing for the same resources, etc.; Awareness of FP’s capability to radically simplify many applications; Awareness of the differences in learning curves; Articulation of side-effects and how they impa...

Good to hear:  

• React is the new Canonical example of one-way data flow. Cycle.js is another popular implementation of uni-directional data flow.
• Angular is a popular framework which uses two-way binding. 

Good to hear:  

• Avoid class hierarchies. 
• Avoid brittle base class problem. 
• Avoid tight coupling. 
• Avoid rigid taxonomy. 
• Avoid the gorilla banana problem. 
• Make code more flexible. 

Good to hear:  

• Positive attitudes toward Microservices, despite higher initial cost vs Monolthic Apps. Despite higher initial cost, Microservices tend to perform and scale better.
• Structure the App so that services are independent from each other. But easy to ...

JavaScript is a multi-paradigm language, supporting imperative/procedural programming along with OOP (Object-Oriented Programming) and functional programming. JavaScript supports OOP with prototypal inheritance.

• Good to hear: Prototypal inheritance (al...