ES6 20 个经常使用的技巧

打乱数组顺序

let arr = ["😄", 67, true, false, "55"]
arr = arr.sort(() => 0.5 - Math.random())
console.log(arr)
// [ '😄', '55', 67, false, true ]

删除数字之外的所有字符

const str = "xieyezi 23213 is 95994 so hansome 223333"
const numbers = str.replace(/\D/g, "")
console.log(numbers)
// 2321395994223333

反转字符串或者单词

const sentence = "xieyezi js so handsome, lol."
const reverseSentence = reverseBySeparator(sentence, "")
console.log(reverseSentence)
// .lol ,emosdnah os sj izeyeix

const reverseEachWord = reverseBySeparator(reverseSentence, " ")
console.log(reverseEachWord)
// izeyeix sj os ,emosdnah .lol

function reverseBySeparator(string, separator) {
  return string.split(separator).reverse().join(separator)
}

将十进制转换为二进制文件或十六进制数

const num = 45
num.toString(2)
num.tostring(16)

合并多个对象

const city = {
  name: "Chongqing",
  population: "1,234,567,890"
}
const location = {
  longitude: "116.4",
  latitude: "39.9"
}
const fullCity = { ...city, ...location }
console.log(fullCity)
// {
//   name: 'Chongqing',
//   population: '1,234,567,890',
//   longitude: '116.4',
//   latitude: '39.9'
// }

=== 和 == 的区别

// ==   ->  类型转换 (浅比较)
// ===  ->  无类型转换 (严格比较)

0 == false // true
0 === false // false
1 == "1" // true
1 === "1" // false
null == undefined // true
null === undefined // false

解构赋值

const forest = {
  location: "Sweden",
  animals: 3,
  animalsTypes: ["Lions", "Tigers", "Bears"]
}

const { location, animals, animalsTypes } = forest
const [lions, tigers, bears] = animalsTypes

console.log(location) // Sweden
console.log(animals) // 3
console.log(lions) // Lions
console.log(tigers) // Tigers
console.log(bears) // Bears

交换变量的值

let bears = "bears"
let tigers = ("tigers"[(bears, tigers)] = [tigers, bears])
console.log(bears) // tigers
console.log(tribes) // bears

1.判断回文字符串

const isRevervse = (str1, str2) => {
  const normalize = (str) => str.toLowerCase().normalize("NFD").split("").reverse().join("")
  return normalize(str1) === str2
}
console.log(isRevervse("anagram", "margana")) // true
console.log(isRevervse("rac", "car")) // true

回文字符串: 正着写和反着写都一样的字符串 (特别感谢@浮生阁阁主勘误) 9. 2.判断两个字符串是否为互相排列

const isAnagram = (str1, str2) => {
  const normalize = (str) => str.toLowerCase().normalize("NFD").split("").sort().join("")
  return normalize(str1) === normalize(str2)
}
console.log(isAnagram("anagram", "nagaram")) // true
console.log(isAnagram("rat", "car")) // false
console.log(isAnagram("heArT", "traEH")) // true

判断两个字符串是否为互相排列: 给定两个字符串,一个是否是另一个的排列 10. 可选链操作符

const player = {
  name: "xieyezi",
  rating: 1000,
  click: () => {
    return "click"
  },
  pass: (teammate) => {
    return `Pass to ${teammate}`
  }
}
console.log(player?.name) // xieyezi
console.log(player?.click?.()) // click
console.log(player?.teammate?.()) // undefined

三目运算符

// condition ? expression if true : expression if false
const oxygen = 10
const diver = oxygen < 10 ? "Low oxygen" : "High oxygen"
console.log(diver) // High oxygen

从数组中随机选择一个值

const elements = [24, "You", 777, "breaking", 99, "full"]
const random = (arr) => arr[Math.floor(Math.random() * arr.length)]
const randomElement = random(elements)
console.log(randomElement) // 777

冻结对象

const octopus = {
  tentacles: 8,
  color: "blue"
}
Object.freeze(octopus)
octopus.tentacles = 10 // Error, 不会改变
console.log(octopus) // { tentacles: 8, color: 'blue'}

删除数组重复的元素

const animals = ["bears", "lions", "tigers", "bears", "lions"]
const unique = (arr) => [...new Set(arr)]

console.log(unique(animals)) // [ 'bears', 'lions', 'tigers' ]

保留指定位小数

const num = 0.123456789
const fixed2 = num.toFixed(2)
const fixed3 = num.toFixed(3)

console.log(fixed2) // 0.12
console.log(fixed3) // 0.123

清空数组

const numbers = [1, 2, 3, 4, 5]
numbers.length = 0

console.log(numbers) // []

从 RGB 转换为 HEX

const rgbToHex = (r, g, b) => {
  const toHex = (num) => {
    const hex = num.toString(16)
    return hex.length === 1 ? `0${hex}` : hex
  }
  return `#${toHex(r)}${toHex(g)}${toHex(b)}`
}
console.log(rgbToHex(46, 32, 67)) // #2e2043

从数组中获取最大值和最小值

const nums = [1, 2, 3, 4, 5, -3, 99, -45, -1]
const max = Math.max(...nums)
const min = Math.min(...nums)
console.log(max) // 99
console.log(min) // -45

空值合并运算符

const nullval = null
cost emptyString = ''
const someNum = 13

const a = nullval ?? 'A default'
const b = emptyString ?? 'B default'
const c = SomeNum ?? 'C default'

console.log(a) // A default
console.log(b) // '' // empty string != undefined or null
console.log(c) // 13

过滤数组中值为 false 的值

const nums = [1, 0, undefined, null, false]
const truthyNums = nums.filter(Boolean)
console.log(truthyNums) // [1]

从CJS和ESM读懂package.json

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ES6 20 个经常使用的技巧 #

ES6 20 个经常使用的技巧