ES11的新特性有哪些

class Hero {
  #aggressivity = 0
  constructor (aggressivity){
   this.#aggressivity = aggressivity
  }
  getHurt(){
   return this.#aggressivity
  }
  setAggressivity(aggressivity){
   this.#aggressivity = aggressivity
  }
}

const shooter = new Hero(100)
let hurt = shooter.getHurt()
console.log(hurt) //100
console.log(shooter.#aggressivity) //Error : Uncaught SyntaxError: Private field '#aggressivity' must be declared in an enclosing class

let aggressivity = parseInt(hurt * 1.1)
shooter.setAggressivity(aggressivity)
console.log(shooter.getHurt()) // 110

let p1 = new Promise((resolve, reject) => {
 resolve('成功了')
})

let p2 = new Promise((resolve, reject) => {
 resolve('success')
})

let p3 = Promse.reject('失敗')

Promise.all([p1, p2]).then((result) => {
 console.log(result) //['成功了', 'success']
}).catch((error) => {
 console.log(error)
})

Promise.all([p1,p3,p2]).then((result) => {
 console.log(result)
}).catch((error) => {
 console.log(error) // 失敗了，打出 '失敗'
})

const promise1 = new Promise((resolve, reject) => {
 setTimeout(resolve, 500, 'one');
});

const promise2 = new Promise((resolve, reject) => {
 setTimeout(resolve, 100, 'two');
});

Promise.race([promise1, promise2]).then((value) => {
 console.log(value);
});
//輸出 "two" 因為promise2返回結(jié)果比promise1快

let allSettled = (funcArr) => {
 return new Promise((resolve) => {
  let sttled = 0
  let result = []
  for(let index = 0;index<funcArr.length;index++){
   const element = funcArr[index]
   element
   .then(res => { 
    result[index] = {
     status: 'fulfilled',
     value: res
    }
   })
   .catch(err => { 
    result[index] = {
     status: 'rejected',
     reason: err
    }
   })
   .finally(() => { ++sttled === funcArr.length && resolve(result) })
  }
 })
}

//使用
const promises = [
  Promise.reject('c'),
  Promise.resolve('a'),
  Promise.resolve('b'),
];

allSettled(promises).then(res => {
  console.log(res)
})

// 打印結(jié)果
// [{"status":"rejected","reason":"c"},
// {"status":"fulfilled","value":"a"},
// {"status":"fulfilled","value":"b"}]

const promises = [
  Promise.reject('c'),
  Promise.resolve('a'),
  Promise.resolve('b'),
];
Promise.allSettled(promises).then(res =>{
 console.log(res)
})
// 打印結(jié)果
// [{"status":"rejected","reason":"c"},
// {"status":"fulfilled","value":"a"},
// {"status":"fulfilled","value":"b"}]

console.log(9999999999999999);  //10000000000000000

// 注意最后一位的數(shù)字
const A = Number.MAX_SAFE_INTEGER + 1
const B = Number.MAX_SAFE_INTEGER + 2

console.log(Number.MAX_SAFE_INTEGER) //9007199254740991
console.log(A) //9007199254740992
console.log(B) //9007199254740992

console.log(A === B) //true

const bigint = 999999999999999999n
const bigintByMethod = BigInt('999999999999999999')
console.log(bigint) //999999999999999999n
console.log(bigintByMethod) //999999999999999999n
console.log(bigint === bigintByMethod) //true

//布爾值
console.log(BigInt(true)) //1n
console.log(BigInt(false)) //0n

console.log(typeof bigint) //"bigint" 

console.log(88n == 88) //true
console.log(88n === 88) //false
console.log(88n+1) //Error =>Uncaught TypeError: Cannot mix BigInt and other types, use explicit conversions

console.log(1n + 2n) //3n
console.log(1n - 2n) //-1n
console.log(+ 1n) //Uncaught TypeError: Cannot convert a BigInt value to a number
console.log(- 1n) //-1n
console.log(10n * 20n) //200n
console.log(23n%10n) //3n
console.log(20n/10n) //2n
......

console.log(25n / 10n) //2n
console.log(29n / 10n) //2n

if (5n) {
  // 這里代碼塊將被執(zhí)行
}

if (0n) {
  // 這里代碼塊不會執(zhí)行
}

0 || 5 // return 5
"" || 5 // return 5
"前端公蝦米" || 'V5' //return "前端公蝦米"

0 ?? 5 //return 0
"" ?? 5 //return ""
null ?? 5 // return 5
undefined ?? 5 // return 5
false ?? 5 //return false
NaN ?? 5 // return NaN

"前端公蝦米" || undefined ?? "Sneaker" //Uncaught SyntaxError: Unexpected token '??'
"前端公蝦米" && undefined ?? "Sneaker" //Uncaught SyntaxError: Unexpected token '??'

("前端公蝦米" || undefined) ?? "(๑•̀ㅂ•́)و✧" //"前端公蝦米"
("前端公蝦米" && null) ?? "一起學習" //"一起學習"

const obj = {
 foo: {
  bar: {
   baz: 42,
  },
 },
}
console.log(obj.fo.bar.baz) //Uncaught TypeError: Cannot read property 'bar' of undefined

在諸如此類的對象里，我們通常進行數(shù)據(jù)安全檢查來訪問嵌套對象，否則將拋錯
if(obj&&obj.foo&&obj.foo.bar){
 console.log(obj.foo.bar.baz) // 42
}

console.log(obj?.foo?.bar?.baz) //42
      
console.log(obj.foo.bar?.baz) //42

//通用導入方式
import("/module/sneaker/test.js")
.then(module => {
 //模塊相關(guān)操作
})

//await
const getModule = await import("/module/sneaker/test.js")

//通過async await
const getUserInfo = async (hasLogin) => {
 if(!hasLogin){
 const user = await import("/module/sneaker/user.js")
  user.getInfo()
 }
}

const string = 'Hello Sneaker,Where is the library?'
const regex = /[A-W]/g
const matches = string.matchAll(regex)

console.log(...matches)
//["H", index: 0, input: "Hello Sneaker,Where is the library?", groups: undefined] 
//["S", index: 6, input: "Hello Sneaker,Where is the library?", groups: undefined] 
//["W", index: 14, input: "Hello Sneaker,Where is the library?", groups: undefined] 

const globalObj = (()=>{
 if(self) return self
 if(window) return window
 if(global) return global
 throw new Error('Sorry!No global obj found')
})

//Browser 
globalThis === window //true

//Webworker
globalThis === self //true

//Node
globalThis === global //true

export * as ns from './module

//等同于
import * as ns from './module'
export {ns}