The constructor method is a special method for creating and initializing an object created with a class.
The extends keyword is used in a class declarations or class expressions to create a class with a child of another class.
The static keyword defines a static method for a class.
The property lets you detect whether a function or constructor was called using the new operator. In constructors and functions instantiated with the new operator, returns a reference to the constructor or function. In normal function calls, is undefined.
JavaScript classes are introduced in ECMAScript 6 are syntactical sugar over JavaScript's existing prototype-based inheritance. The class syntax is not introducing a new object-oriented inheritance model to JavaScript. JavaScript classes provide a much simpler and clearer syntax to create objects and deal with inheritance.
The class expression is one way to define a class in ECMAScript 2015 (ES6). Similar to function expressions, class expressions can be named or unnamed. If named, the name of the class is local to the class body only. JavaScript classes are using prototype-based inheritance.
The class declaration creates a new class with a given name using prototype-based inheritance.
The super keyword is used to call functions on an object's parent.