What is the role of encapsulation in object-oriented programming?

Encapsulation in object-oriented programming is a principle that allows hiding the internal implementation details of an object and providing access to data and methods only through a defined interface.

The role of encapsulation:

• Data protection: prevents direct access to internal fields of an object, helping to avoid unintended modifications.
• Simplifies usage: users interact with the object through public methods without worrying about internal implementation.
• Increases flexibility: internal implementation can be changed without affecting code that uses the object.

Example in JavaScript (Node.js):

class User {
  #password; // private field

  constructor(name, password) {
    this.name = name;
    this.#password = password;
  }

  checkPassword(input) {
    return input === this.#password;
  }
}

const user = new User('Alice', 'secret');
console.log(user.name); // Alice
console.log(user.checkPassword('secret')); // true
// user.#password - error, access denied

Thus, encapsulation helps create more reliable and maintainable code.