JavaScript : Object-Oriented Programming

Protecting and hiding data

When we design classes, we want to make sure that all the necessary data is available to the methods that will operate on this data; therefore, we encapsulate the data. However, we just want the relevant information to be visible to the users of our classes that will create instances, change values of accessible attributes or properties, and call the available methods. Therefore, we want to hide or protect some data that is just needed for internal use. We don't want accidental changes to sensitive data.

For example, when we create a new instance of any dog breed, we can use its name and birth date as two parameters for a constructor. The constructor initializes the values of two internal fields: m_name and m_birthDate ...