物件與函式

• 屬性(property)：靜態的資料，用於描述物件的狀態；
• 方法(method)：物件的功能，或說物件的行為；

物件中的this代表是誰呼叫這個函式

直接把物件傳給函式

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

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

搭配for-in迴圈(利用typeOf !=='function' 過濾掉function):

function showDetail (user) {
  for (let prop in user) {
    if (typeof user[prop] !== 'function') {
      console.log(user[prop])
    }
  }
}
showDetail(user)

把物件傳給回傳值

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}

創建一個遊戲角色:

把物件當成函式的回傳值

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}

在javascript裡面常見的場景，〔函式可以當成值〕

• 存進變數
• 當成物件屬性
• 當成另一個函式的回傳值
• 當成另一個函式的參數

把函式放進變數:

簡單的函式:

function greet(name) {
  return `Hi, ${name}`
}

把函式當成值，放進變數

const greet = function (name) {
  return `Hi, ${name}`
}

但是結果是一樣的，greet('peter') // hi, peter

把函式放成物件屬性:

const user = {
  name: ['Peter', 'Lee'],
  gender: 'Male',
  age: 41,
  greet: function () {
    console.log(`Hello! I am ${this.name[0]}.`)
  },
  run: function () { console.log('run!')},
}
user.greet() // Hello! I am Peter.

當成另一個函式的回傳值:

當成另一個函式的參數:

function game () {
  console.log("Let's play game!")
  return 'I am happy!'
}
//增加這個函式
function study(){
  console.log("Let's go to school.")
  return 'I am tired.'
}
//修改這個函式
function breakfast (callback) {
  console.log(`I finished my breakfast.`)
  return callback() 
}
//呼叫時才決定吃完早餐要去讀書
const today = breakfast(study)
console.log(today)

匿名函式:

function game () {
  console.log("Let's play game!")
  return 'I am happy!'
}
// 註解起來
// function study(){
//   console.log("Let's go to school.")
//   return 'I am tired.'
// }
function breakfast (callback) {
  console.log(`I finished my breakfast.`)
  return callback() 
}
//直接把匿名函式傳入，效果相同
const today = breakfast(function (){
  console.log("Let's go to school.")
  return 'I am tired.'
})
console.log(today)