Encapsulation is one of the four fundamental OOP concepts. It is the bundling of data and the methods that operate on that data into a single unit, i.e., class. It is used

• to hide the internal state of an object from the outside world and to only expose the necessary functionality.
• to prevent the accidental modification of data.
• to provide a way to access the data in a controlled manner.

JavaScript uses closures to implement encapsulation, which allows developers to create private variables and methods that cannot be accessed from outside the object.

Example

function Person(name, age) {
  let privateName = name;
  this.age = age;

  this.getName = function () {
    return privateName;
  };
}

let person = new Person("John", 25);
console.log(person.name); // undefined
console.log(person.age); // 25
console.log(person.getName()); // John

In the above example, the privateName variable is a private variable that cannot be accessed from outside the object. The getName method is a public method that can be accessed from outside the object.

Conclusion

• Encapsulation is the bundling of data and methods that operate on that data into a single unit.
• JavaScript uses closures to implement encapsulation.
• Encapsulation is used to hide the internal state of an object from the outside world and to only expose the necessary functionality.
• Encapsulation is used to prevent the accidental modification of data.
• Encapsulation is used to provide a way to access the data in a controlled manner.