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es6基础(2)

es6标准入门

Iterator

遍历器接口

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let s = function* (){
    yield '🍨';
    yield '🍔'
}
const r = s()
console.log(r.next())
console.log(r.next())
console.log(r.next())

上面用的不多

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const arr = ['🍐','🍊','🥭']
// for of直接得到值
for(let v of arr){
    console.log(v)
}
// for in得到索引 
for(let i in arr){
    console.log(i)
}

// 🍐
// 🍊
// 🥭 
// 0
// 1
// 2

const obj = {
    a: '🍐',
    b: '🍊',
    c: '🥭'
}
for(let v of obj){
    console.log(v)
}
// VM289:6 Uncaught TypeError: obj is not iterable

Generator

Class

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class Person{
    constructor(age){
        this.age = age
    }
}
const xiaowang = new Person(30)
console.log(xiaowang.age)
// 30
// 新的代码块
class Person{
    constructor(age){
        this.age = age
    }
    tell(){
        console.log(`小王的年龄是${this.age}`)
    }
}
class Man extends Person{
    constructor(age){
        super(age)
        this.arr = []
    }
    tell(){
        super.tell()
        console.log('halo')
    }
    set menu(data){
        this.arr.push(data)
    }
    get menu(){
        return this.arr
    }
    static init(){
        console.log('static')
    }
}
Man.init()
const xiaowang = new Man(30)
console.log(xiaowang.tell())
xiaowang.menu = '🍅'
console.log(xiaowang.menu)
// static
// 小王的年龄是30
// halo
// ["🍅"]

Set Map

Set

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let arr = new Set('🍦🍔🥪')
arr.add('🌭')
arr.add('🍲')
arr.add('🍲')
console.log(arr)
console.log(arr.has('🍔'))
arr.delete('🍔')
for(let t of arr){
    console.log(t)
}
arr.clear()
console.log(arr)

// Set(5) {"🍦", "🍔", "🥪", "🌭", "🍲"} 自动去重
// true
// 🍦
// 🥪
// 🌭
// 🍲 
// Set(0) {}

Map

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let food = new Map()
let fruit = {},cook = function (){}
food.set(fruit,'🍋')
food.set(cook,'🍔')
console.log(food)
console.log(food.get(fruit))
console.log(food.size)
food.delete(fruit)
console.log(food.size)
food.clear()
console.log(food.size)

// Map(2) {{…} => "🍋", ƒ => "🍔"}
// [[Entries]]
//     0: {Object => "🍋"}
//     key: {}
//     value: "🍋"
//     1: {function (){} => "🍔"}
//     key: ƒ ()
//     value: "🍔"
//     size: (...)
//     __proto__: Map 
// 🍋
// 2
// 1
// 0

数组去重

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const arr = [1,2,3,4,4,4,5]
const r = [...new Set(arr)]
console.log(r)
// (5) [1, 2, 3, 4, 5]

Moudle

index.js

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const test  =  function test(arg){
    // xxx
}
export test

const go  =  function go(arg){
    // xxx
}
export go
// 或 exprot {test, go}
// export default

run.js

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import {test, go} from 'index.js'
// import data from 'index.js'
// data.test()
// data.go()
JavaScript