Used to make the fields of a class private and accessible only through the methods of the class.
It is a technique which helps to ensure the integrity of the data stored in the fields, as well as to provide a clear and consistent interface for interacting with the class.
In JavaScript, fields can be encapsulated by defining them within the constructor function of a class and using getter and setter methods to access and modify their values.
For example, consider the following class, which has a publicly accessible field name:
}
}
}
To encapsulate the name field, we can remove the assignment in the constructor and add a getter and setter method:
}
}
}
}
}
Now, the name field can only be accessed or modified through the name getter and setter methods. Attempting to access the field directly will result in an error. This ensures that the field's value can only be changed in a controlled and predictable way, which can be useful for maintaining the integrity of data in an application.
Encapsulating fields can also provide a consistent and clear interface for interacting with a class. For example, in the above example, the sayHello method references the name property via the getter method, this way the user of the class has no way of modifying the name property without going through the setter method.
In summary, encapsulating fields in JavaScript classes can provide a way to maintain the integrity of data in an application and provide a clear and consistent interface for interacting with a class. It is a best practice to encapsulate fields that are used to store data that should be protected from direct modification, and to use getter and setter methods to access and modify these fields in a controlled and predictable way.