来源 | https://segmentfault.com/a/1190000022623676

作者 | Eno_Yao

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https://github.com/Wscats/CV/issues/32

数组 Array

1、数组去重

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

2、查找数组最大

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

3、查找数组最小

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

4、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)  );}

5、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);}

6、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),    []  );}

7、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));}

8、返回两个数组中相同的元素

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

9、从右删除 n 个元素

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

10、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;}

11、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);}

12、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];}

13、返回数组头元素

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

14、返回数组末尾元素

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

15、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

16、判读浏览器是否支持 CSS 属性

/** * 告知浏览器支持的指定css属性情况 * @param {String} key - css属性，是属性的名字，不需要加前缀 * @returns {String} - 支持的属性情况 */function validateCssKey(key) {const jsKey = toCamelCase(key); // 有些css属性是连字符号形成if (jsKey in document.documentElement.style) {return key;  }let validKey = "";// 属性名为前缀在js中的形式，属性值是前缀在css中的形式// 经尝试，Webkit 也可是首字母小写 webkitconst prefixMap = {Webkit: "-webkit-",Moz: "-moz-",ms: "-ms-",O: "-o-",  };for (const jsPrefix in prefixMap) {const styleKey = toCamelCase(`${jsPrefix}-${jsKey}`);if (styleKey in document.documentElement.style) {      validKey = prefixMap[jsPrefix] + key;break;    }  }return validKey;}
/** * 把有连字符号的字符串转化为驼峰命名法的字符串 */function toCamelCase(value) {return value.replace(/-(\w)/g, (matched, letter) => {return letter.toUpperCase();  });}
/** * 检查浏览器是否支持某个css属性值（es6版） * @param {String} key - 检查的属性值所属的css属性名 * @param {String} value - 要检查的css属性值（不要带前缀） * @returns {String} - 返回浏览器支持的属性值 */function valiateCssValue(key, value) {const prefix = ["-o-", "-ms-", "-moz-", "-webkit-", ""];const prefixValue = prefix.map((item) => {return item + value;  });const element = document.createElement("div");const eleStyle = element.style;// 应用每个前缀的情况，且最后也要应用上没有前缀的情况，看最后浏览器起效的何种情况// 这就是最好在prefix里的最后一个元素是''  prefixValue.forEach((item) => {    eleStyle[key] = item;  });return eleStyle[key];}
/** * 检查浏览器是否支持某个css属性值 * @param {String} key - 检查的属性值所属的css属性名 * @param {String} value - 要检查的css属性值（不要带前缀） * @returns {String} - 返回浏览器支持的属性值 */function valiateCssValue(key, value) {var prefix = ["-o-", "-ms-", "-moz-", "-webkit-", ""];var prefixValue = [];for (var i = 0; i < prefix.length; i++) {    prefixValue.push(prefix[i] + value);  }var element = document.createElement("div");var eleStyle = element.style;for (var j = 0; j < prefixValue.length; j++) {    eleStyle[key] = prefixValue[j];  }return eleStyle[key];}
function validCss(key, value) {const validCss = validateCssKey(key);if (validCss) {return validCss;  }return valiateCssValue(key, value);}

摘自 https://juejin.im/post/5e58f398f265da574a1eb569

17、当前网页地址

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

18、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,  };}

19、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      ),      {}    );}

20、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);}

21、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);  }}

22、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);  }}

23、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

24、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());}

25、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();  }}

26、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

27、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

28、固定滚动条

/** * 功能描述：一些业务场景，如弹框出现时，需要禁止页面滚动，这是兼容安卓和 iOS 禁止页面滚动的解决方案 */
let scrollTop = 0;
function preventScroll() {// 存储当前滚动位置  scrollTop = window.scrollY;
// 将可滚动区域固定定位，可滚动区域高度为 0 后就不能滚动了document.body.style["overflow-y"] = "hidden";document.body.style.position = "fixed";document.body.style.width = "100%";document.body.style.top = -scrollTop + "px";// document.body.style['overscroll-behavior'] = 'none'}
function recoverScroll() {document.body.style["overflow-y"] = "auto";document.body.style.position = "static";// document.querySelector('body').style['overscroll-behavior'] = 'none'
window.scrollTo(0, scrollTop);}

29、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)  );}

30、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;}

31、获取元素 css 样式

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

32、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

33、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();

34、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

35、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,");}

36、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;  }}

36个工作中常用的JavaScript函数片段