What is the reason to use the 'new' keyword at Derived.prototype = new Base

Question

What does the following code do:

WeatherWidget.prototype = new Widget;

where Widget is a constructor, and I want to extend the

Answer 1

JavaScript functions are "MULTIPLE(2) PERSONALITIES"!!!

They are regular-functions with input and output, which we call like function().

Also they are constructors of JS-objects, when we use the new keyword. >>>BUT<<< the new created objects are NOT INSTANCES of the constructors (like the objects of classes in class-based inheritance). The new objects are instances of the object of the prototype property of the constructor.

Then in WeatherWidget.prototype = you put the object you want to inherit its properties to the objects the constructor will create, which usually is new function() and not a function.

JavaScript created HUGE confusion in the programming community by naming the objects created by constructors, INSTANCES of them with the instanceof keyword.
> function f(){}
undefined
> new f() instanceof f
true