プロジェクトでよく使われるES 6

const breakfast = () => ['cake', 'coffee', 'apple']
let [dessert, drink, fruit] = breakfast()
console.info(dessert, drink, fruit) // 'cake' 'coffee' 'apple'

const breakfast = () => {
    return {
        dessert: 'cake',
        drink: 'coffee',
        fruit: 'apple'
    }
}
let {dessert, drink, fruit} = breakfast()
console.info(dessert, drink, fruit) // 'cake' 'coffee' 'apple'

//    Array   concat()   
let breakfast = ['cake', 'coffee', 'apple']
let food = ['rice', ...breakfast]
console.info(...breakfast, food) // 'cake' 'coffee' 'apple', ["rice", "cake", "coffee", "apple"]

//     
let food = {}
let drink = 'hot drink'
food[drink] = 'milk'
console.log(food['hot drink']) // 'milk'

let food = {}
let drink = 'hot drink'
food[drink] = 'milk'

let dessert = 'cake'
food.fruit = 'banane'

let breakfast = Object.assign({}, {dessert}, food) // {dessert}      
console.log(breakfast) // {dessert: "cake", hot drink: "milk", fruit: "banane"}

let fruit = new Set(['apple', 'banane', 'orange'])
/*     ，           ，            ：[...new Set(arr)] */
fruit.add('pear')
/*      */
console.log(fruit.size) // 4
/*         */
console.log(fruit.has('apple')) // true
/*      */
fruit.delete('banana') 

console.log(fruit) // Set(4) {"apple", "banane", "orange", "pear"}
/*    */
fruit.forEach(item => {
    console.log(item)
})
/*    */
fruit.clear()

console.log(fruit) // Set(0) {}

let food = new Map()
let fruit = {}, cook = function(){}, dessert = '  '
food.set(fruit, 'apple')
food.set(cook, 'knife')
food.set(dessert, 'cake')

console.log(food, food.size) // Map(3) {{…} => "apple", ƒ => "knife", "  " => "cake"} 3

console.log(food.get(fruit)) // "apple"
console.log(food.get(dessert)) // "cake"

food.delete(dessert)
console.log(food.has(dessert)) // false

food.forEach((value, key) => {
    console.log(`${key} = ${value}`) // [object Object] = apple    function(){} = knife
})

food.clear()
console.log(food) // Map(0) {}

function* calc(num){
    yield num+1
    yield num-2
    yield num*3
    yield num/4
    return num
}
let cal = calc(4)
console.info(
    cal.next(), // {value: 5, done: false}
    cal.next(), // {value: 2, done: false}
    cal.next(), // {value: 12, done: false}
    cal.next(), // {value: 1, done: false}
    cal.next(), // {value: 4, done: true}       done:true
    cal.next() // {value: undefined, done: true}
)

class Chef{
    constructor(food){
        this.food = food;
        this.dish = [];
    }
    get menu(){ //      （Getter must not have any formal parameters.)
        console.log('getter   ')
        console.log(this.dish)
        return this.dish
    }
    set menu(dish){ //        （Setter must have exactly one formal parameter.）
        console.log('setter   ')
        this.dish.push(dish)
    }
    cook(){
        console.log(this.food)
    }
}
let Gu = new Chef('vegetables');
Gu.cook() // "vegetables"
console.log(Gu.menu) // "get   " []

Gu.menu = 'egg' // "setter   "
Gu.menu = 'fish' // "setter   "

console.log(Gu.menu); // "getter   " ["egg", "fish"]

class Person {
    constructor(name, birth){
        this.name = name
        this.birth = birth
    }
    intro(){
        return `${this.name}    ${this.birth}`
    }
}

class One extends Person {
    constructor(name, birth){
        super(name, birth)
    }
}

let z = new Person('zz', '01-09')
let x = new One('xx', '01-09')

console.log(z.intro(), x.intro()) // "zz    01-09" "xx    01-09"
//    ES5       
/* function Person(name, birth) {
    this.name = name;
    this.birth = birth;
}
Person.prototype.intro = function () {
    return this.name + '\u7684\u751F\u65E5\u662F' + this.birth;
};
function One(name, birth) {
    Person.apply(this, arguments);
}
One.prototype = new Person();
var z = new Person('zz', '01-09');
var x = new One('xx', '01-09');

console.log(z.intro(), x.intro()); // "zz    01-09" "xx    01-09" */

function ajax(fn){
    setTimeout(()=>{
        console.log('    ')
        fn()
    },1000)
}
ajax(()=>{
    ajax(()=>{
        ajax(()=>{
            ajax(()=>{
                console.log('    4')
            })
            console.log('    3')
        })
        console.log('    2')
    })
    console.log('    1')
})
/*
      ：
        1s：          1
        2s:           2
        3s：          3
        4s:           4
*/

function delay(word){
    return new Promise((reslove,reject) => {
        setTimeout(()=>{
            console.log('    ')
            reslove(word)
        },1000)
    })
}
delay('    1')
    .then(word=>{
        console.log(word)
        return delay('    2')
    })
    .then(word=>{
        console.log(word)
        return delay('    3')
    })
    .then(word=>{
        console.log(word)
        return delay('    4')
    })
    .then(word=>{
        console.log(word)
    })
    .catch()

function delay(word){
    return new Promise((reslove, reject) => {
        setTimeout(()=>{
            console.log('    ')
            reslove(word)
        },1000)
    })
}

const start = async () => {
    const word1 = await delay('    1')
    console.log(word1)

    const word2 = await delay('    2')
    console.log(word2)

    const word3 = await delay('    3')
    console.log(word3)
    
    const word4 = await delay('    4')
    console.log(word4)
}

start()