🍎객체 지향 프로그래밍 (4) Prototype

function Person(name, first, second) {
  this.name = name
  this.first = first
  this.second = second
  this.sum = function() {
    return this.first + this.second
  }
}

var kim = new Person('kim', 10, 20)
var lee = new Person('lee', 10, 10)

function Person(name, first, second, third) {
  this.name = name
  this.first = first
  this.second = second
}

Person.prototype.sum = function() {
  return 'prototype : ' + (this.first + this.second)
}

var kim = new Person('kim', 10, 20);
var lee = new Person('lee', 10, 10);
console.log("kim.sum()", kim.sum());
console.log("lee.sum()", lee.sum());

kim.sum() prototype : 30
lee.sum() prototype : 20
undefined

Person.prototype.sum = function() {
  return 'modified prototype : ' + (this.first + this.second)
}
ƒ () {
  return 'modified prototype : ' + (this.first + this.second)
}
console.log("kim.sum()", kim.sum());
console.log("lee.sum()", lee.sum());
kim.sum() modified prototype : 30
lee.sum() modified prototype : 20
undefined

kim.sum = function(){
    return 'this : '+(this.first+this.second);
}
ƒ (){
    return 'this : '+(this.first+this.second);
}
console.log("kim.sum()", kim.sum());
console.log("lee.sum()", lee.sum());
kim.sum() this : 30
lee.sum() modified prototype : 20
undefined

kim.sum = function() {
  return 'this : ' + (this.first + this.second)
}

Person.prototype.sum = function() {
  return 'modified prototype : ' + (this.first + this.second)
}

생성자.prototype.함수이름 = function() {
  return ...
}