Creating Object

 

var Person = function(name,yearOfBirth, job){
    this.name = name;
    this.yearOfBirth = yearOfBirth;
    this.job = job;
}

Person.prototype.calculateAge = function(){
    console.log(2020 - this.yearOfBirth);
}

Person.prototype.lastNAme = 'Smith';

var john = new Person('John',1999,'teacher');   //instantiation
var mark = new Person('Mark',1979,'retired');

john.calculateAge();	//21
mark.calculateAge();	//41

console.log(john.lastNAme);	//'Smith'
console.log(mark.lastNAme);	//'Smith'

 

 

//Object.create
var personProto = {
    calculateAge : function(){
        console.log(2020 - this.yearOfBirth);
        
    }
}
//방법1
var john = Object.create(personProto);
john.name = 'John';
john.yearOfBirth = 1990;
john.job = 'teacher';


//방법2
var mark = Object.create(personProto,{
    name: {value : 'Mark'},
    yearOfBirth : {value:1980},
    job: {value : 'designer'}
});

Primitive VS Object

// Primitives vs objects

//Primitive
var a = 23;
var b = a;
a = 46;
console.log(a); //46
console.log(b); //23

//Object
var obj1 = {
    name : "John",
    age : 23
}

var obj2 = obj1;

obj1.age = 30;
console.log(obj1.age);  //30
console.log(obj2.age);  //30


//Functions
var age = 27;
var obj = {
    name : 'Jonas',
    city : 'Lisbon'
};

function change(a,b){
    a = 30;
    b.city  = 'SanFrancisco'
}

change(age,obj);

console.log(age);   //27
console.log(obj.city);  //SanFrancisco

/*when pass a primitive into the function
a simple copy is created.
So we can change 'a' as much as we want,
it will never affect the variable on the outside
because it is a primitive.
But when we pass the object,
it's not really the object that we pass,
but the reference to the object.
*/

 

오브젝트를 변수에 담을때 변수에 실제로 들어가는 값은 오브젝트 그 실제 값이 아니라 오브젝트의 레퍼런스가 들어간다.

 

 

 

 

참조 : Udemy - The Complete JavaScript Course 2020 : Build Real Projects!

 

https://stackoverflow.com/questions/3127429/how-does-the-this-keyword-work 여기서 두번째 답변

How does the "this" keyword work?

https://jojoldu.tistory.com/7?category=635878

prototype 이란?