Encapsulation – encapsulation refers to the bundling of data with the methods that operate on that data, or the restricting of direct access to some of an object’s components.^[1] Encapsulation is used to hide the values or state of a structured data object inside a class, preventing direct access to them by clients in a way that could expose hidden implementation details or violate state invariance maintained by the methods.

Function overloading or method overloading is the ability to create multiple functions of the same name with different implementations. Calls to an overloaded function will run a specific implementation of that function appropriate to the context of the call, allowing one function call to perform different tasks depending on context.

An interface is a description of the actions that an object can do

Closure gives you access to an outer function’s scope from an inner function

Cracking technical coding interview in JS

https://github.com/careercup/CtCI-6th-Edition-JavaScript/blob/master/chapter01/1.1%20-%20Is%20Unique/isUnique.js