JavaScript Beginners Tutorial 21 | OOP | Encapsulation with example

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------------ OTHERS ------------

Keep Learning,
Raghav

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[alexlui]

after i called the setter method, i can access all the data and even change the data...how is this encapsulation??

[RC-zfhp]

I think you made a mistake. Nothing is encapsulated there. You can either use a closure or the new feature of using a private class feature.

// Closure
class Employee {
constructor(name, id, phoneNo) {
this.getEmpName = function () {
return name;
};

this.getEmpId = function () {
return id;
};

this.getEmpPhoneNo = function () {
return phoneNo;
};
}
}

let emp1 = new Employee('John', 1001, 9874511);
console.log(emp1.name); // undefined
console.log(emp1.id); // undefined
console.log(emp1.phoneNo); // undefined

// John
console.log(emp1.getEmpId()); // 1001
// 9874511


// Or Using a Private Field

class Employee {
#EmpName;
#EmpId;
#EmpPhoneNo;

setEmpDeatils(name, id, phoneNo) {
this.#EmpName = name;
this.#EmpId = id;
this.#EmpPhoneNo = phoneNo;
}

getEmpName() {
return this.#EmpName;
}

getEmpId() {
return this.#EmpId;
}

getEmpPhoneNo() {
return this.#EmpPhoneNo;
}
}

const emp1 = new Employee();
emp1.setEmpDeatils('John', 1001, 9874511);
console.log(emp1);
console.log(emp1.#EmpName); // Private field '#num' must be declared in an enclosing class
console.log(emp1.#EmpId); //Private field '#num' must be declared in an enclosing class
//Private field '#num' must be declared in an enclosing class
console.log(emp1.getEmpId()); //1001;
// John
//9874511

[sajidsaiyed]

Raghav some doubts. Please correct me. With your emp1 object, i can direct access all your attributes so how it can be encapsulation.

[barryreddy]

Hey, where did you declare the access specifier for those variables, name and id, should be initialized as #name, #id, so that they are made private and could be accessed only using the getter methods. Please correct that. The following code works.

class PrivateEngineer{

#name = 'default';
#id = 0;

setName(name, id){
this.#name =name;
this.#id = id;
}

getName(){
return this.#name;
}

getId(){
return this.#id;
}

}

// Encapsulation
let emp = new PrivateEngineer();
emp.setName('Bharath', 2005);
console.log(emp.getName());
console.log(emp.getId());

[CaliburPANDAs]

You can still access the api publicly. How is this encapsulation?

[aarthi]

Can you give an example in a real time project to implement encapsulation, inheritance, polymorphism, abstractions

[kacperkepinski]

I have to invoke funcion in constructor, do you know how to do it?

[CodeWavewithShahHussain]

On doubt sir in javaScript interface is avalible?

[TheKidrock]

How did you set private data i can't see it here?

[mohitsharma-ptjd]

can i also get data by using console.log(emp1.phoneNo)

[TheKidrock]

above setEmpDetails() should be set name, id, phoneNo as if they are private (#name, #id, #phoneNo) or protected (_name, _id, _phoneNo) and after that this.name and this.id, this.phoneNo as like if private this.#name or protected this._name the rest follows.