How to understand that the code is good?

Philosophy

Reality

A bit of spells

DRY

Don't repeat yourself

KISS

Keep it simple, stupid

YAGNI

You aren't gonna need it  

SOLID

Single responsibility principle

a class should have only a single responsibility

Open/closed principle

"software entities … should be open for extension, but closed for modification."

Liskov substitution principle

"objects in a program should be replaceable with instances of their subtypes"

Interface segregation principle

"many client-specific interfaces are better than one general-purpose interface.

Dependency inversion principle

one should "depend upon abstractions, [not] concretions.

GRASP
SOA
MSA

Patterns

It's easy

Anti-Patterns

• https://en.wikipedia.org/wiki/Anti-pattern

Code review process

Code style

https://github.com/airbnb/javascript

https://standardjs.com/​

Linters

ESLint