物件導向程式設計 (Object-oriented programming, OOP) 是一種使用 abstraction 概念的程式設計方式，由先前所建立的技術所組成:

• 模組化 (modularity)
• 多型 (polymorphism)
• 封裝 (encapsulation)

JavaScript 是一個以雛型為基礎 (Prototype-based) 的程式設計語言 -> 物件導向程式設計
JavaScript 透過函數來當類別的建構子，但無類別敘述 -> 與其他物件導向程式設計的差異

**創立一個物件 1 **

// Object literal
// empty
var city = {};

// with properties
var book = {
    title: 'JavaScript',
    price: 150,
    publish: 1990,
    category: ['Science fiction', 'adventure'],
    isOnSale: false
};

點記法 (Dot notation)
透過 . 存取物件的屬性與函式

book.title; // output JavaScript
book.category; // output ['Science fiction', 'adventure']
book.category[1]; // output adventure

括弧記法 (Bracket notation)
透過 [] 存取物件的屬性與函式

book['title']; // output JavaScript
book['category']; // output ['Science fiction', 'adventure']
book['category'][1]; // output adventure

創立一個物件 2

// new Object
var book = new Object();
book.title = JavaScript;
book.price = 150;
book['category'] = ['Science fiction', 'adventure'];

Objects and methods
在物件裡寫 methods -> 並透過 this 指向進行寫值、計算

// basic
var book = {
    title: 'JavaScript',
    price: 150,
    publish: 1990,
    category: ['Science fiction', 'adventure'],
    isOnSale: false,
    countYear: function(publish){
        return 2020 - publish;
    }
};

console.log(book.countYear(1990)); // 30

//get variable by this
var book = {
    title: 'JavaScript',
    price: 150,
    publish: 1990,
    category: ['Science fiction', 'adventure'],
    isOnSale: false,
    countYear: function() {
        this.age = 2020 - this.publish;
    }
};

book.countYear();
book.age; // output 30 -> 寫入成功!

課程 : https://www.udemy.com/course/the-complete-javascript-course/
來源 :
https://pjchender.blogspot.com/2016/01/javascriptobject.html
https://developer.mozilla.org/zh-TW/docs/Learn/JavaScript/Objects/Basics
https://developer.mozilla.org/zh-TW/docs/Web/JavaScript/Introduction_to_Object-Oriented_JavaScript