前端40个基础小技巧

const createArr = (n) => Array.from(new Array(n), (v, i) => i)

const arr = createArr(100) // 0 - 99 数组

const createArr = (n) => new Array(n).fill(0).map((v, i) => i)

createArr(100) // 0 - 99 数组

const randomSort = list => list.sort(() => Math.random() - 0.5)

randomSort([0,1,2,3,4,5,6,7,8,9]) // 随机排列结果

const removeDuplicates = list => [...new Set(list)]

removeDuplicates([0, 0, 2, 4, 5]) // [0,2,4,5]

const removeDuplicates = list => Array.from(new Set(list))

removeDuplicates([0, 0, 2, 4, 5]) // [0,2,4,5]

const intersection = (a, ...arr) => [...new Set(a)].filter((v) => arr.every((b) => b.includes(v)))

intersection([1, 2, 3, 4], [2, 3, 4, 7, 8], [1, 3, 4, 9])

// [3, 4]

const indexOfMax = (arr) => arr.reduce((prev, curr, i, a) => (curr > a[prev] ? i : prev), 0);

indexOfMax([1, 3, 9, 7, 5]); // 2

const indexOfMin = (arr) => arr.reduce((prev, curr, i, a) => (curr < a[prev] ? i : prev), 0)

indexOfMin([2, 5, 3, 4, 1, 0, 9]) // 5

const closest = (arr, n) => arr.reduce((prev, curr) => (Math.abs(curr - n) < Math.abs(prev - n) ? curr : prev))

closest([29, 87, 8, 78, 97, 20, 75, 33, 24, 17], 50) // 33

const zip = (...arr) => Array.from({ length: Math.max(...arr.map((a) => a.length)) }, (_, i) => arr.map((a) => a[i]))

zip([1,2,3,4], ['a', 'b', 'c', 'd'], ['A', 'B', 'C', 'D'])

// [[1, 'a', 'A'], [2, 'b', 'B'], [3, 'c', 'C'], [4, 'd', 'D']]

const transpose = (matrix) => matrix[0].map((col, i) => matrix.map((row) => row[i]));

transpose(

    [              // [

        [1, 2, 3], //      [1, 4, 7],

        [4, 5, 6], //      [2, 5, 8],

        [7, 8, 9], //      [3, 6, 9],

     ]             //  ]

 );

const toDecimal = (num, n = 10) => num.toString(n)

// 假设数字 10 要转换成 2 进制

toDecimal(10, 2) // '1010'

// 10 的 2 进制为 1010

const toDecimalism = (num, n = 10) => parseInt(num, n)

toDecimalism(1010, 2)

const formatPhone = (str, sign = '-') => str.replace(/(\W|\s)/g, "").split(/^(\d{3})(\d{4})(\d{4})$/).filter(item => item).join(sign)

formatPhone('13123456789') // '131-2345-6789'

formatPhone('13 1234 56 789', ' ') // '131 2345 6789'

const setTrimOut = str => str.replace(/\s\s+/g, ' ')

const str = setTrimOut('hello,   jack') //

const reload = () => location.reload();

reload()

const goToTop = () => window.scrollTo(0, 0);

goToTop()

const scrollToTop = (element) =>

  element.scrollIntoView({ behavior: "smooth", block: "start" })

scrollToTop(document.body)

const scrollToBottom = (element) =>

  element.scrollIntoView({ behavior: "smooth", block: "end" })

  scrollToBottom(document.body)

const isIE = !!document.documentMode;

const stripHtml = (html) => new DOMParser().parseFromString(html, 'text/html').body.textContent || '';

stripHtml('<div>test</div>') // 'test'

const goTo = (url) => (location.href = url);

const copy = (text) => navigator.clipboard?.writeText && navigator.clipboard.writeText(text)

copy('你需要粘贴的文本')

const isToday = (date) => date.toISOString().slice(0, 10) === new Date().toISOString().slice(0, 10)

const formatYmd = (date) => date.toISOString().slice(0, 10);

formatYmd(new Date())

const formatSeconds = (s) => new Date(s * 1000).toISOString().substr(11, 8)

formatSeconds(200) // 00:03:20

const getFirstDate = (d = new Date()) => new Date(d.getFullYear(), d.getMonth(), 1);

getFirstDate(new Date('2022-04')) // Fri Apr 01 2022 00:00:00 GMT+0800 (中国标准时间)

const getLastDate = (d = new Date()) => new Date(d.getFullYear(), d.getMonth() + 1, 0);

getLastDate(new Date('2023-03-04')) // Fri Mar 31 2023 00:00:00 GMT+0800 (中国标准时间)

const getDaysNum = (year, month) => new Date(year, month, 0).getDate()

const day = getDaysNum(2024, 2) // 29

const isAsyncFunction = (v) => Object.prototype.toString.call(v) === '[object AsyncFunction]'

isAsyncFunction(async function () {}); // true

const toFixed = (n, fixed) => `${n}`.match(new RegExp(`^-?\d+(?:.\d{0,${fixed}})?`))[0]

toFixed(10.255, 2) // 10.25

const round = (n, decimals = 0) => Number(`${Math.round(`${n}e${decimals}`)}e-${decimals}`)

round(10.255, 2) // 10.26

const replenishZero = (num, len, zero = 0) => num.toString().padStart(len, zero)

replenishZero(8, 2) // 08

const removeNullUndefined = (obj) => Object.entries(obj).reduce((a, [k, v]) => (v == null ? a : ((a[k] = v), a)), {});

removeNullUndefined({name: '', age: undefined, sex: null}) // { name: '' }

const invert = (obj) => Object.keys(obj).reduce((res, k) => Object.assign(res, { [obj[k]]: k }), {})

invert({name: 'jack'}) // {jack: 'name'}

const strParse = (str) => JSON.parse(str.replace(/(\w+)\s*:/g, (_, p1) => `"${p1}":`).replace(/\'/g, "\""))

strParse('{name: "jack"}')

const isEqual = (...objects) => objects.every(obj => JSON.stringify(obj) === JSON.stringify(objects[0]))

isEqual({name: 'jack'}, {name: 'jack'}) // true

isEqual({name: 'jack'}, {name: 'jack1'}, {name: 'jack'}) // false

const getRandomColor = () => `#${Math.floor(Math.random() * 0xffffff).toString(16)}`

getRandomColor() // '#4c2fd7'

const hexToRgb = hex => hex.replace(/^#?([a-f\d])([a-f\d])([a-f\d])$/i, (_, r, g, b) => `#${r}${r}${g}${g}${b}${b}`).substring(1).match(/.{2}/g).map((x) => parseInt(x, 16));

hexToRgb('#00ffff'); // [0, 255, 255]

hexToRgb('#0ff'); // [0, 255, 255]

const randomIp = () =>

    Array(4)

        .fill(0)

        .map((_, i) => Math.floor(Math.random() * 255) + (i === 0 ? 1 : 0))

        .join('.');

const uuid = (a) => (a ? (a ^ ((Math.random() * 16) >> (a / 4))).toString(16) : ([1e7] + -1e3 + -4e3 + -8e3 + -1e11).replace(/[018]/g, uuid))

uuid()

const getCookie = () => document.cookie

    .split(';')

    .map((item) => item.split('='))

    .reduce((acc, [k, v]) => (acc[k.trim().replace('"', '')] = v) && acc, {})

getCookie()

const sleep = async (t) => new Promise((resolve) => setTimeout(resolve, t));

sleep(2000).then(() => {console.log('time')});