1.获取多个数的平均值
使用reduce我们可以非常方便的得到一组数组的平均值。
const average = (…args) => args.reduce((a, b) => a + b, 0) / args.length
average(0, 1, 2, -1, 9, 10) // 3.5
2.检查数字是偶数还是奇数
如何判断一个数是奇数还是偶数?
const isEven = num => num % 2 === 0
isEven(2) // true :可以被二整除的
isEven(1) // false:不能被二整除的
3.删除数组中的重复元素
要删除数组中的重复元素,使用 Set 将变得非常容易。
const uniqueArray = (arr) => […new Set(arr)]
uniqueArray([ 1, 1, 2, 3, 4, 5, -1, 0 ]) // [1, 2, 3, 4, 5, -1, 0]
4.数组复杂去重
需要使用对象的唯一标识
let art = this.formLabelAlign.YouCeShuZhuangTuShuJu.filter((item, index) => {
return this.formLabelAlign.YouCeShuZhuangTuShuJu.findIndex(obj => obj === item) === index;
});
5.检查一个对象是否为空对象
const isEmpty = obj => Reflect.ownKeys(obj).length === 0 && obj.constructor === Object
isEmpty({}) // true
isEmpty({ name: ‘小明’ }) // false
6.反转字符串
const reverseStr = str => str.split(‘’).reverse().join(”)
reverseStr(‘qwerty’) //ytrewq
7.计算两个日期之间的间隔
const dayDiff = (d1, d2) => Math.ceil(Math.abs(d1.getTime() – d2.getTime()) / 86400000)
dayDiff(new Date(“2023-06-23”), new Date(“1997-05-31”)) // 9519
8.查找该日期是一年中的第几天
const dayInYear = (d) => Math.floor((d – new Date(d.getFullYear(), 0, 0)) / 1000 / 60 / 60 / 24)
dayInYear(new Date(‘2023/06/23’)) // 174
9..将字符串的第一个字母大写
const capitalize = str => str.charAt(0).toUpperCase() + str.slice(1)
capitalize(“hello fatfish”) // Hello fatfish
10.生成指定长度的随机字符串
const gRtring = length => […Array(length)].map(() => Math.random().toString(36)[2]).join(”)
gRtring (12) // cysw0ertyoqx
gRtring (12) // uoqauger8qws
11.获取两个整数之间的随机整数
const random = (min, max) => Math.floor(Math.random() * (max – min + 1) + min)
random(1, 100) // 27
random(1, 100) // 84
random(1, 100) // 55
12.指定数字四舍五入
const round = (n, d) => Number(Math.round(n + “e” + d) + “e-” + d)
round(3.1415926, 3) //3.142
round(3.1415926, 1) //3.1
13.清除所有cookie
const clearCookies = document.cookie.split(‘;’).forEach(cookie => document.cookie = cookie.replace(/^ +/, ”).replace(/=.*/, `=;expires=${new Date(0).toUTCString()};path=/`))
14.检测是否为深色模式
const isDarkMode = window.matchMedia && window.matchMedia(‘(prefers-color-scheme: dark)’).matches
console.log(isDarkMode)
15.滚动到页面顶部
const goToTop = () => window.scrollTo(0, 0)
goToTop()
16.判断是否是苹果设备
const isAppleDevice = () => /Mac|iPod|iPhone|iPad/.test(navigator.platform)
isAppleDevice()
17.随机布尔值
const randomBoolean = () => Math.random() >= 0.5
randomBoolean()
18.获取变量的类型
const typeOf = (obj) => Object.prototype.toString.call(obj).slice(8, -1).toLowerCase()
typeOf(”) // string
typeOf(0) // number
typeOf() // undefined
typeOf(null) // null
typeOf({}) // object
typeOf([]) // array
typeOf(0) // number
typeOf(() => {}) // function
19.判断当前选项卡是否处于活动状态
const checkTabInView = () => !document.hidden
20.检查某个元素是否获得焦点
const isFocus = (ele) => ele === document.activeElement
21.随机IP
const gRIP = () => {
return Array.from({length: 4}, () => Math.floor(Math.random() * 256)).join(‘.’);
}
gRIP () // 210.178.178.123
gRIP () // 240.21.189.141
22.数据补位
// 实例
let date = new Date()
let at = String(date .getMonth()).padStart(2,'0')
console.log(at) // 09
23.两个数组之间的穿插
let A1 = [3,3,3]
let A2 = [2,2,]
var rectifyIndex = Math.max(A1.length, A2.length)
for (var i = 0; i < A1; i++) {
if (i < A1.length) {
mergedArray.push(A1[i]);
}
if (i < A2.length) {
mergedArray.push( A2[i]);
}
}
console.log(rectifyIndex ) // [3,2,3,2,3]
24.冒泡排序
let arrray = [12, 30, 58, 365, 157, 9];
let len = arrray.length
for (var i = 0; i < len - 1; i++) {
for (var j = 0; j < len - 1 - i; j++) {
if (arrray[j] > arrray[j -1]) {
var temp = arrray[j];
arrray[j] = arrray[j - 1];
arrray[j - 1] = temp;
}
}
}
console.log(arrray)