Introduction to Encapsulation in JavaScript | CodeSignal Learn

Introduction to Encapsulation in JavaScript | CodeSignal Learn

Let's look at the following JavaScript example to get a better understanding of encapsulation using private class fields:

JavaScript

class Person {
    #name;
    #age;

    // Constructor
    constructor(name, age) {
        this.#name = name;
        this.#age = age;
    }

    // Setters
    setName(name) {
        this.#name = name;
    }

    setAge(age) {
        if (age >= 0) {
            this.#age = age;
        } else {
            console.error('Age cannot be negative.');
        }
    }

    // Getters
    getName() {
        return this.#name;
    }

    getAge() {
        return this.#age;
    }
}

// Example usage
const person = new Person('Alice', 30);
person.setName('Bob');
person.setAge(25);

console.log(`Name: ${person.getName()}, Age: ${person.getAge()}`);

In this example, we have a Person class with private fields #name and #age. The class provides methods (setName, setAge, getName, and getAge) for manipulating and accessing these private fields.

If we skip setters and getters and make the data fields accessible, we lose control over the data and can't enforce constraints or validations. Encapsulation allows us to protect the object's internal state and provide controlled access to it. Additionally, encapsulation enables us to include logic within setter methods, such as validating that the age is not set to a negative value.