prototype與__proto__區別

Each constructor is a function that has a property named “prototype” that is used to implement prototype-based inheritance and shared properties. Every object created by a constructor has an implicit reference (called the object's prototype) to the value of its constructor's “prototype” property.
When a constructor creates an object, that object implicitly references the constructor's prototype property for the purpose of resolving property references. The constructor's prototype property can be referenced by the program expression constructor.prototype, and properties added to an object's prototype are shared, through inheritance, by all objects sharing the prototype. Alternatively, a new object may be created with an explicitly specified prototype by using the Object.create built-in function.