無序集合，強調的則是屬性名稱，屬性名稱必須要有相對應的值，用大括號 {} 包覆起來的資料，有key、value

物件宣告

物件實字

//較常用
var 物件名稱 = {
    屬性: 值(字串、陣列、函式、物件、數值...),
}
//值可以是function、array、object....
var userInfo = {
	firstName: 'Jay',
  lastName: 'Chen', //string
	ages: 22,//number
	interest: ['聽音樂', '看電影', '運動'],//array
	address: { //object
		country: '台灣',
		city: '台北',
		locate: '101'
	},
	fullName: function(){ //function
		return this.firstName + ' ' + this.lastName;
		//this是一個物件參考，指物件本身
	}
}

建構式

用new創建物件

var 物件名稱 = new Object();

var userInfo = new Object();
userInfo.name = 'Jay';
userInfo.age = 23;
console.log(userInfo); //Object { age: 23, name: "Jay" }
console.log(userInfo.name); //Jay

物件取值

利用(.)運算子

靜態存取，無法用數字、變數存取

var userInfo = {
	firstName: 'Jay',
  lastName: 'Chen', //string
	ages: 22,//number
	interest: ['聽音樂', '看電影', '運動'],//array
	address: { //object
		country: '台灣',
		city: '台北',
		locate: '101'
	},
	fullName: function(){ //function
		return this.firstName + ' ' + this.lastName;
		//this是一個物件參考，指物件本身
	}
}
//物件讀取:物件名稱.屬性
//取function
userInfo.fullName(); //Jay Chen
//取陣列
var interest = userInfo.interest[0];
console.log(interest); //聽音樂

關聯式陣列

動態存取資料，[]可以放字串、變數、數字...方式取值

var userInfo = {
	firstName: 'Jay',
  lastName: 'Chen', //string
	ages: 22,//number
	interest: ['聽音樂', '看電影', '運動'],//array
}
var city=['台北','台中','台南','高雄'];
// 取物件裡面的物件
//物件讀取:物件名稱['屬性']
console.log(userInfo['firstName']); //台灣

//傳入變數來取值
var personName = 'firstName';
console.log(userInfo[personName]); //Jay

//動態訪問屬性
for(i=0;i<4;i++){
   userInfo["city"+i]=city[i];
}
console.log(userInfo);

物件新增/修改

var obj = {};
obj.name = 'John';
obj['age'] = 22;
console.log(obj); //{name: 'John', age: 22}
obj.name = 'Jay'; //修改值
console.log(obj);//{name: 'Jay', age: 22}

物件刪除

var obj = {
	name: 'Jay',
	age: 22,
	city: 'Taipei'
}
delete obj.city;
delete obj['age'];
console.log(obj); {name: 'Jay'}