Javascript based on three major characteristics of objects (encapsulation, inheritance, polymorphism) _ javascript skills

This article mainly introduces three main features of Javascript based on objects, including encapsulation, inheritance, and Polymorphism. if you are interested, you can refer to the three features of Javascript based on objects and C ++, java object-oriented features are the same as those of encapsulation, inheritance, and polymorphism ). However, the implementation methods are different, and their basic concepts are similar. In fact, apart from the three main features, there is also a common feature called abstract, which is why we sometimes see four features of object-oriented in some books.
I. encapsulation
Encapsulation encapsulates the abstracted data and the operations on the data, and the data is protected internally. other parts of the program are only authorized operations (member methods ), to operate the data.
Case: