36个工作中常用的JavaScript函数片段

数组 Array

数组去重

function noRepeat(arr) { return [...new Set(arr)];}

查找数组最大

function arrayMax(arr) { return Math.max(...arr);}

查找数组最小

function arrayMin(arr) { return Math.min(...arr);}

返回已 size 为长度的数组分割的原数组

function chunk(arr, size = 1) { return Array.from( { length: Math.ceil(arr.length / size), }, (v, i) => arr.slice(i * size, i * size + size) );}

检查数组中某元素出现的次数

function countOccurrences(arr, value) { return arr.reduce((a, v) => (v === value ? a + 1 : a + 0), 0);}

扁平化数组

默认 depth 全部展开

function flatten(arr, depth = -1) { if (depth === -1) { return [].concat( ...arr.map((v) => (Array.isArray(v) ? this.flatten(v) : v)) ); } if (depth === 1) { return arr.reduce((a, v) => a.concat(v), []); } return arr.reduce( (a, v) => a.concat(Array.isArray(v) ? this.flatten(v, depth - 1) : v), [] );}

对比两个数组并且返回其中不同的元素

function diffrence(arrA, arrB) { return arrA.filter((v) => !arrB.includes(v));}

返回两个数组中相同的元素

function intersection(arr1, arr2) { return arr2.filter((v) => arr1.includes(v));}

从右删除 n 个元素

function dropRight(arr, n = 0) { return n < arr.length ? arr.slice(0, arr.length - n) : [];}

截取第一个符合条件的元素及其以后的元素

function dropElements(arr, fn) { while (arr.length && !fn(arr[0])) arr = arr.slice(1); return arr;}

返回数组中下标间隔 nth 的元素

function everyNth(arr, nth) { return arr.filter((v, i) => i % nth === nth - 1);}

返回数组中第 n 个元素

支持负数

function nthElement(arr, n = 0) { return (n >= 0 ? arr.slice(n, n + 1) : arr.slice(n))[0];}

返回数组头元素

function head(arr) { return arr[0];}

返回数组末尾元素

function last(arr) { return arr[arr.length - 1];}

数组乱排

function shuffle(arr) { let array = arr; let index = array.length; while (index) { index -= 1; let randomInedx = Math.floor(Math.random() * index); let middleware = array[index]; array[index] = array[randomInedx]; array[randomInedx] = middleware; } return array;}

浏览器对象 BOM

判读浏览器是否支持 CSS 属性

摘自 https:///post/5e58f398f265da574a1eb569

返回当前网页地址

function currentURL() { return window.location.href;}

获取滚动条位置

function getScrollPosition(el = window) { return { x: el.pageXOffset !== undefined ? el.pageXOffset : el.scrollLeft, y: el.pageYOffset !== undefined ? el.pageYOffset : el.scrollTop, };}

获取 url 中的参数

function getURLParameters(url) { return url .match(/([^?=&]+)(=([^&]*))/g) .reduce( (a, v) => ( (a[v.slice(0, v.indexOf("="))] = v.slice(v.indexOf("=") + 1)), a ), {} );}

页面跳转，是否记录在 history 中

function redirect(url, asLink = true) { asLink ? (window.location.href = url) : window.location.replace(url);}

滚动条回到顶部动画

function scrollToTop() { const scrollTop = document.documentElement.scrollTop || document.body.scrollTop; if (scrollTop > 0) { window.requestAnimationFrame(scrollToTop); window.scrollTo(0, c - c / 8); } else { window.cancelAnimationFrame(scrollToTop); }}

复制文本

function copy(str) { const el = document.createElement("textarea"); el.value = str; el.setAttribute("readonly", ""); el.style.position = "absolute"; el.style.left = "-9999px"; el.style.top = "-9999px"; document.body.appendChild(el); const selected = document.getSelection().rangeCount > 0 ? document.getSelection().getRangeAt(0) : false; el.select(); document.execCommand("copy"); document.body.removeChild(el); if (selected) { document.getSelection().removeAllRanges(); document.getSelection().addRange(selected); }}

检测设备类型

function detectDeviceType() { return /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test( navigator.userAgent ) ? "Mobile" : "Desktop";}

Cookie

增

function setCookie(key, value, expiredays) { var exdate = new Date(); exdate.setDate(exdate.getDate() + expiredays); document.cookie = key + "=" + escape(value) + (expiredays == null ? "" : ";expires=" + exdate.toGMTString());}

删

function delCookie(name) { var exp = new Date(); exp.setTime(exp.getTime() - 1); var cval = getCookie(name); if (cval != null) { document.cookie = name + "=" + cval + ";expires=" + exp.toGMTString(); }}

查

function getCookie(name) { var arr, reg = new RegExp("(^| )" + name + "=([^;]*)(;|$)"); if ((arr = document.cookie.match(reg))) { return arr[2]; } else { return null; }}

日期 Date

时间戳转换为时间

默认为当前时间转换结果

isMs 为时间戳是否为毫秒

function timestampToTime(timestamp = Date.parse(new Date()), isMs = true) { const date = new Date(timestamp * (isMs ? 1 : 1000)); return `${date.getFullYear()}-${ date.getMonth() + 1 < 10 ? "0" + (date.getMonth() + 1) : date.getMonth() + 1 }-${date.getDate()} ${date.getHours()}:${date.getMinutes()}:${date.getSeconds()}`;}

文档对象 DOM

固定滚动条

判断当前位置是否为页面底部

返回值为 true/false

function bottomVisible() { return ( document.documentElement.clientHeight + window.scrollY >= (document.documentElement.scrollHeight || document.documentElement.clientHeight) );}

判断元素是否在可视范围内

partiallyVisible 为是否为完全可见

function elementIsVisibleInViewport(el, partiallyVisible = false) { const { top, left, bottom, right } = el.getBoundingClientRect(); return partiallyVisible ? ((top > 0 && top < innerHeight) || (bottom > 0 && bottom < innerHeight)) && ((left > 0 && left < innerWidth) || (right > 0 && right < innerWidth)) : top >= 0 && left >= 0 && bottom <= innerHeight && right <= innerWidth;}

获取元素 css 样式

function getStyle(el, ruleName) { return getComputedStyle(el, null).getPropertyValue(ruleName);}

进入全屏

function launchFullscreen(element) { if (element.requestFullscreen) { element.requestFullscreen(); } else if (element.mozRequestFullScreen) { element.mozRequestFullScreen(); } else if (element.msRequestFullscreen) { element.msRequestFullscreen(); } else if (element.webkitRequestFullscreen) { element.webkitRequestFullScreen(); }}launchFullscreen(document.documentElement);launchFullscreen(document.getElementById("id")); //某个元素进入全屏

退出全屏

function exitFullscreen() { if (document.exitFullscreen) { document.exitFullscreen(); } else if (document.msExitFullscreen) { document.msExitFullscreen(); } else if (document.mozCancelFullScreen) { document.mozCancelFullScreen(); } else if (document.webkitExitFullscreen) { document.webkitExitFullscreen(); }}exitFullscreen();

全屏事件

document.addEventListener("fullscreenchange", function (e) { if (document.fullscreenElement) { console.log("进入全屏"); } else { console.log("退出全屏"); }});

数字 Number

数字千分位分割

function commafy(num) { return num.toString().indexOf(".") !== -1 ? num.toLocaleString() : num.toString().replace(/(d)(?=(?:d{3})+$)/g, "$1,");}

生成随机数

function randomNum(min, max) { switch (arguments.length) { case 1: return parseInt(Math.random() * min + 1, 10); case 2: return parseInt(Math.random() * (max - min + 1) + min, 10); default: return 0; }}

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