JavaScript Encapsulation

Encapsulation is an object-oriented programming concept that allows us to keep the data and behavior of an object together by protecting the internal state of an object from outside interference. Encapsulation provides a way to hide the complexity of an object’s functions from other parts of the application.

Syntax

class ClassName {
  constructor() {
    // private variable
    var privateVar = 0;
    // private method
    var privateMethod = function() {
      console.log('Private method');
    }
    // public method
    this.publicMethod = function() {
      console.log('Public method');
    }
  }
}

Example

Let’s consider an example of encapsulation in JavaScript where we will create a Person class that has a private member age. We will expose a public method getAge() to get the value of age and a private method setAge() to set the value of age.

class Person {
  constructor() {
    // private variable
    var age = 0;
    // private method
    var setAge = function(newAge) {
      age = newAge;
    }
    // public method
    this.getAge = function() {
      return age;
    }
    // public method
    this.setAge = function(newAge) {
      if(newAge > 0 && newAge < 120){
        setAge(newAge);
      } else{
        console.log("Invalid Age");
      }
    }
  }
}

Output

Let's create a Person object and set the age using the setAge() method and retrieve the age of the person using the getAge() method.

const person = new Person();
person.setAge(30);
console.log(person.getAge()); // Output: 30

Explanation

In the above example, we have created a Person class with a private member age. We have also defined two public methods getAge() and setAge(). The setAge() method is a private method that sets the value of age and is only called from within the Person class. It checks whether the value of age is in the valid range before setting it. The getAge() method is a public method that returns the value of age to the caller.

By encapsulating age within the Person class, we have ensured that it can be accessed only through the getAge() and setAge() methods, which are public methods of the Person class. This helps in maintaining the integrity of the Person object’s data.

Use

The main use of encapsulation is to protect the internal state of an object from outside interference. Encapsulation helps to reduce complexity, increase security, and simplifies code maintenance.

Encapsulation is also useful in creating reusable code. By encapsulating the behavior of an object within it, we can reuse the object in different parts of the application without worrying about its internal details.

Important Points

• Encapsulation is a concept in object-oriented programming that allows us to keep the data and behavior of an object together by protecting the internal state of an object from outside interference.
• The private members of an object are only accessible from within the object.
• The public members of an object are accessible from outside the object.
• Encapsulation helps in reducing complexity, increasing security, and simplifying code maintenance.
• Encapsulation also helps in creating reusable code.

Summary

Encapsulation is an object-oriented programming concept that allows us to keep the data and behavior of an object together by protecting the internal state of an object from outside interference. Encapsulation helps in reducing complexity, increasing security, and simplifying code maintenance. By encapsulating the behavior of an object within it, we can reuse the object in different parts of the application without worrying about its internal details.