15条你可能不知道的JS高效技巧

1、延迟函数delay

const delay = ms => new Promise((resolve, reject) => setTimeout(resolve, ms)) const getData = status => new Promise((resolve, reject) => {     status ? resolve('done') : reject('fail') }) const getRes = async (data) => {     try {         const res = await getData(data)         const timestamp = new Date().getTime()         await delay(1000)         console.log(res, new Date().getTime() - timestamp)     } catch (error) {         console.log(error)     } } getRes(true) // 隔了1秒

2、分割指定长度的元素数组

 const listChunk = (list, size = 1, cacheList = []) => {     const tmp = [...list]     if (size <= 0) {         return cacheList     }     while (tmp.length) {         cacheList.push(tmp.splice(0, size))     }     return cacheList } console.log(listChunk([1, 2, 3, 4, 5, 6, 7, 8, 9])) // [[1], [2], [3], [4], [5], [6], [7], [8], [9]] console.log(listChunk([1, 2, 3, 4, 5, 6, 7, 8, 9], 3)) // [[1, 2, 3], [4, 5, 6], [7, 8, 9]] console.log(listChunk([1, 2, 3, 4, 5, 6, 7, 8, 9], 0)) // [] console.log(listChunk([1, 2, 3, 4, 5, 6, 7, 8, 9], -1)) // []

3、获取数组交集

 const intersection = (list, ...args) => list.filter(item => args.every(list => list.includes(item))) console.log(intersection([2, 1], [2, 3])) // [2] console.log(intersection([1, 2], [3, 4])) // []

4、函数柯里化

 const curring = fn => {     const { length } = fn     const curried = (...args) => {         return (args.length >= length               ? fn(...args)               : (...args2) => curried(...args.concat(args2)))     }     return curried } const listMerge = (a, b, c) => [a, b, c] const curried = curring(listMerge) console.log(curried(1)(2)(3)) // [1, 2, 3] console.log(curried(1, 2)(3)) // [1, 2, 3] console.log(curried(1, 2, 3)) // [1, 2, 3]

5、字符串前面空格去除与替换

 const trimStart = str => str.replace(new RegExp('^([\s]*)(.*)$'), '$2') console.log(trimStart(' abc ')) // abc console.log(trimStart('123 ')) // 123

6、字符串后面空格去除与替换

 const trimEnd = str => str.replace(new RegExp('^(.*?)([\s]*)$'), '$1') console.log(trimEnd(' abc ')) //   abc console.log(trimEnd('123 ')) // 123

7、获取当前子元素是其父元素下子元素的排位

 const getIndex = el => {     if (!el) {         return -1     }     let index = 0     do {         index++     } while (el = el.previousElementSibling);     return index }

8、获取当前元素相对于document的偏移量

 const getOffset = el => {     const {         top,         left     } = el.getBoundingClientRect()     const {         scrollTop,         scrollLeft     } = document.body     return {         top: top + scrollTop,         left: left + scrollLeft     } }

9、获取元素类型

const dataType = obj => Object.prototype.toString.call(obj).replace(/^[object (.+)]$/, '$1').toLowerCase();

10、判断是否是移动端

 const isMobile = () => 'ontouchstart' in window

11、fade动画

 const fade = (el, type = 'in') {     el.style.opacity = (type === 'in' ? 0 : 1)     let last = +new Date()     const tick = () => {         const opacityValue = (type === 'in'                              ? (new Date() - last) / 400                             : -(new Date() - last) / 400)         el.style.opacity = +el.style.opacity + opacityValue         last = +new Date()         if (type === 'in'           ? (+el.style.opacity < 1)           : (+el.style.opacity > 0)) {             requestAnimationFrame(tick)         }     }     tick() } 

12、将指定格式的字符串解析为日期字符串

const dataPattern = (str, format = '-') => {     if (!str) {         return new Date()     }     const dateReg = new RegExp(`^(\d{2})${format}(\d{2})${format}(\d{4})$`)     const [, month, day, year] = dateReg.exec(str)     return new Date(`${month}, ${day} ${year}`) } console.log(dataPattern('12-25-1995')) // Mon Dec 25 1995 00:00:00 GMT+0800 (中国标准时间)

13、禁止网页复制粘贴

 const html = document.querySelector('html') html.oncopy = () => false html.onpaste = () => false

14、input框限制只能输入中文

 const input = document.querySelector('input[type="text"]') const clearText = target => {     const {         value     } = target     target.value = value.replace(/[^u4e00-u9fa5]/g, '') } input.onfocus = ({target}) => {     clearText(target) } input.onkeyup = ({target}) => {     clearText(target) } input.onblur = ({target}) => {     clearText(target) } input.oninput = ({target}) => {     clearText(target) }

15、去除字符串中的html代码

 const removehtml = (str = '') => str.replace(/<[/!]*[^<>]*>/ig, '') console.log(removehtml('<h1>哈哈哈哈<呵呵呵</h1>')) // 哈哈哈哈<呵呵呵