###### tags: `ALPHACampWeek1`

物件操作
===

typeof判斷型別：這個真的很好用
---
if(typeof(performance[person]) ==='number'){
sum+=performance[person]
}

點記法與標記法
---
// dot notation
myPhone.name // 'myPhone'
// bracket notation
myPhone['name'] // 'myPhone'

列舉出所有的值：for-in 迴圈
---
for (let key in myPhone) {
console.log(myPhone[key])
}

一口氣取得資料
---
取出所有的 key 值 - Object.keys()
取出所有的 value - Object.values()
取出所有的 pair - Object.entries()

物件導向程式設計
---
const user = {
name: ['Peter', 'Lee'],
gender: 'Male',
age: 41,
greet: function () {
console.log(`Hello! I am ${this.name[0]}.`)
},
run: function () { console.log('run!')}
}
- 呼叫
user.greet() // Hello! I am Peter.
user.run() // run!

直接將物件當參數
---
如果我現在想要寫一支函式 showDetail() 來印出 user 的所有屬性，以下的方法看起來蠻笨的：

function showDetail(name, gender, age) {
console.log(`${name[0]} ${name[1]}`)
console.log(gender)
console.log(age)
}
showDetail(user.name, user.gender, user.age)

---

更好的方式是直接將物件傳給函式：

function showDetail(user) {
console.log(`${user.name[0]} ${user.name[1]}`)
console.log(user.gender)
console.log(user.age)
}
showDetail(user)

甚至能直接用for-in判斷物件是否為function
function showDetail (user) {
for (let prop in user) {
if (typeof user[prop] !== 'function') {
console.log(user[prop])
}
}
}
showDetail(user)

RPG要這樣寫
---
function createPlayer (name, hp, mp) {
return {
name: name,
hp: hp,
mp: mp
}
}

const player1 = createPlayer('Magician', 30, 100)
const player2 = createPlayer('Warrior', 100, 30)

console.log(player1) // {name: "Magician", hp: 30, mp: 100}
console.log(player2) // {name: "Warrior", hp: 100, mp: 30}

- 會比這樣寫來的好

當我們需要產生很多個格式相同的物件時，以往我們可能會這樣做：

player1 = {
name: 'Magician',
hp: 30,
mp: 100
}

player2 = {
name: 'Warrior',
hp: 100,
mp: 30
}

console.log(player1) // {name: "Magician", hp: 30, mp: 100}
console.log(player2) // {name: "Warrior", hp: 100, mp: 30}