JavaScript中的50+个实用工具函数（总结）

function isStatic(value) { return ( typeof value === 'string' || typeof value === 'number' || typeof value === 'boolean' || typeof value === 'undefined' || value === null ) }

function isPrimitive(value) { return isStatic(value) || typeof value === 'symbol' }

function isObject(value) { let type = typeof value; return value != null && (type == 'object' || type == 'function'); }

function isObjectLike(value) { return value != null && typeof value == 'object'; }

function getRawType(value) { return Object.prototype.toString.call(value).slice(8, -1) } // getoRawType([]) ⇒ Array

function isPlainObject(obj) { return Object.prototype.toString.call(obj) === '[object Object]' }

function isArray(arr) { return Object.prototype.toString.call(arr) === '[object Array]' } // 将isArray挂载到Array上 Array.isArray = Array.isArray || isArray;

function isRegExp(value) { return Object.prototype.toString.call(value) === '[object RegExp]' }

function isDate(value) { return Object.prototype.toString.call(value) === '[object Date]' }

function isNative(value) { return typeof value === 'function' && /native code/.test(value.toString()) }

function isFunction(value) { return Object.prototype.toString.call(value) === '[object Function]' }

function isLength(value) { return typeof value == 'number' && value > -1 && value % 1 == 0 && value <= Number.MAX_SAFE_INTEGER; }

function isArrayLike(value) { return value != null && isLength(value.length) && !isFunction(value); }

function isEmpty(value) { if (value == null) { return true; } if (isArrayLike(value)) { return !value.length; } else if (isPlainObject(value)) { for (let key in value) { if (hasOwnProperty.call(value, key)) { return false; } } } return false; }

function cached(fn) { let cache = Object.create(null); return function cachedFn(str) { let hit = cache[str]; return hit || (cache[str] = fn(str)) } }

let camelizeRE = /-(\w)/g; function camelize(str) { return str.replace(camelizeRE, function(_, c) { return c ? c.toUpperCase() : ''; }) } //ab-cd-ef ==> abCdEf //使用记忆函数 let _camelize = cached(camelize)

let hyphenateRE = /\B([A-Z])/g; function hyphenate(str){ return str.replace(hyphenateRE, '-$1').toLowerCase() } //abCd ==> ab-cd //使用记忆函数 let _hyphenate = cached(hyphenate);

function capitalize(str) { return str.charAt(0).toUpperCase() + str.slice(1) } // abc ==> Abc //使用记忆函数 let _capitalize = cached(capitalize)

function extend(to, _form) { for(let key in _form) { to[key] = _form[key]; } return to }

Object.assign = Object.assign || function() { if (arguments.length == 0) throw new TypeError('Cannot convert undefined or null to object'); let target = arguments[0], args = Array.prototype.slice.call(arguments, 1), key; args.forEach(function(item) { for (key in item) { item.hasOwnProperty(key) && (target[key] = item[key]) } }) return target }

let clone = Object.assign({}, target);

let clone = JSON.parse( JSON.stringify(target) )

function clone(value, deep) { if (isPrimitive(value)) { return value } if (isArrayLike(value)) { //是类数组 value = Array.prototype.slice.call(vall) return value.map(item => deep ? clone(item, deep) : item) } else if (isPlainObject(value)) { //是对象 let target = {}, key; for (key in value) { value.hasOwnProperty(key) && ( target[key] = deep ? clone(value[key], value[key] )) } } let type = getRawType(value); switch(type) { case 'Date': case 'RegExp': case 'Error': value = new window[type](value); break; } return value }

//运行环境是浏览器 let inBrowser = typeof window !== 'undefined'; //运行环境是微信 let inWeex = typeof WXEnvironment !== 'undefined' && !!WXEnvironment.platform; let weexPlatform = inWeex && WXEnvironment.platform.toLowerCase(); //浏览器 UA 判断 let UA = inBrowser && window.navigator.userAgent.toLowerCase(); let isIE = UA && /msie|trident/.test(UA); let isIE9 = UA && UA.indexOf('msie 9.0') > 0; let isEdge = UA && UA.indexOf('edge/') > 0; let isAndroid = (UA && UA.indexOf('android') > 0) || (weexPlatform === 'android'); let isIOS = (UA && /iphone|ipad|ipod|ios/.test(UA)) || (weexPlatform === 'ios'); let isChrome = UA && /chrome\/\d+/.test(UA) && !isEdge;

function getExplorerInfo() { let t = navigator.userAgent.toLowerCase(); return 0 <= t.indexOf("msie") ? { //ie < 11 type: "IE", version: Number(t.match(/msie ([\d]+)/)[1]) } : !!t.match(/trident\/.+?rv:(([\d.]+))/) ? { // ie 11 type: "IE", version: 11 } : 0 <= t.indexOf("edge") ? { type: "Edge", version: Number(t.match(/edge\/([\d]+)/)[1]) } : 0 <= t.indexOf("firefox") ? { type: "Firefox", version: Number(t.match(/firefox\/([\d]+)/)[1]) } : 0 <= t.indexOf("chrome") ? { type: "Chrome", version: Number(t.match(/chrome\/([\d]+)/)[1]) } : 0 <= t.indexOf("opera") ? { type: "Opera", version: Number(t.match(/opera.([\d]+)/)[1]) } : 0 <= t.indexOf("Safari") ? { type: "Safari", version: Number(t.match(/version\/([\d]+)/)[1]) } : { type: t, version: -1 } }

function isPCBroswer() { let e = navigator.userAgent.toLowerCase() , t = "ipad" == e.match(/ipad/i) , i = "iphone" == e.match(/iphone/i) , r = "midp" == e.match(/midp/i) , n = "rv:1.2.3.4" == e.match(/rv:1.2.3.4/i) , a = "ucweb" == e.match(/ucweb/i) , o = "android" == e.match(/android/i) , s = "windows ce" == e.match(/windows ce/i) , l = "windows mobile" == e.match(/windows mobile/i); return !(t || i || r || n || a || o || s || l) }

function unique(arr){ if(!isArrayLink(arr)){ //不是类数组对象 return arr } let result = [] let objarr = [] let obj = Object.create(null) arr.forEach(item => { if(isStatic(item)){//是除了symbol外的原始数据 let key = item + '_' + getRawType(item); if(!obj[key]){ obj[key] = true result.push(item) } }else{//引用类型及symbol if(!objarr.includes(item)){ objarr.push(item) result.push(item) } } }) return resulte }

window.Set = window.Set || (function () { function Set(arr) { this.items = arr ? unique(arr) : []; this.size = this.items.length; // Array的大小 } Set.prototype = { add: function (value) { // 添加元素,若元素已存在,则跳过，返回 Set 结构本身。 if (!this.has(value)) { this.items.push(value); this.size++; } return this; }, clear: function () { //清除所有成员，没有返回值。 this.items = [] this.size = 0 }, delete: function (value) { //删除某个值，返回一个布尔值，表示删除是否成功。 return this.items.some((v, i) => { if(v === value){ this.items.splice(i,1) return true } return false }) }, has: function (value) { //返回一个布尔值，表示该值是否为Set的成员。 return this.items.some(v => v === value) }, values: function () { return this.items }, } return Set; }());

function repeat(str, n) { let res = ''; while(n) { if(n % 2 === 1) { res += str; } if(n > 1) { str += str; } n >>= 1; } return res }; //repeat('123',3) ==> 123123123

function dateFormater(formater, t){ let date = t ? new Date(t) : new Date(), Y = date.getFullYear() + '', M = date.getMonth() + 1, D = date.getDate(), H = date.getHours(), m = date.getMinutes(), s = date.getSeconds(); return formater.replace(/YYYY|yyyy/g,Y) .replace(/YY|yy/g,Y.substr(2,2)) .replace(/MM/g,(M<10?'0':'') + M) .replace(/DD/g,(D<10?'0':'') + D) .replace(/HH|hh/g,(H<10?'0':'') + H) .replace(/mm/g,(m<10?'0':'') + m) .replace(/ss/g,(s<10?'0':'') + s) } // dateFormater('YYYY-MM-DD HH:mm', t) ==> 2019-06-26 18:30 // dateFormater('YYYYMMDDHHmm', t) ==> 201906261830

function dateStrForma(str, from, to){ //'20190626' 'YYYYMMDD' 'YYYY年MM月DD日' str += '' let Y = '' if(~(Y = from.indexOf('YYYY'))){ Y = str.substr(Y, 4) to = to.replace(/YYYY|yyyy/g,Y) }else if(~(Y = from.indexOf('YY'))){ Y = str.substr(Y, 2) to = to.replace(/YY|yy/g,Y) } let k,i ['M','D','H','h','m','s'].forEach(s =>{ i = from.indexOf(s+s) k = ~i ? str.substr(i, 2) : '' to = to.replace(s+s, k) }) return to } // dateStrForma('20190626', 'YYYYMMDD', 'YYYY年MM月DD日') ==> 2019年06月26日 // dateStrForma('121220190626', '----YYYYMMDD', 'YYYY年MM月DD日') ==> 2019年06月26日 // dateStrForma('2019年06月26日', 'YYYY年MM月DD日', 'YYYYMMDD') ==> 20190626 // 一般的也可以使用正则来实现 //'2019年06月26日'.replace(/(\d{4})年(\d{2})月(\d{2})日/, '$1-$2-$3') ==> 2019-06-26

function getPropByPath(obj, path, strict) { let tempObj = obj; path = path.replace(/\[(\w+)\]/g, '.$1'); //将[0]转化为.0 path = path.replace(/^\./, ''); //去除开头的. let keyArr = path.split('.'); //根据.切割 let i = 0; for (let len = keyArr.length; i < len - 1; ++i) { if (!tempObj && !strict) break; let key = keyArr[i]; if (key in tempObj) { tempObj = tempObj[key]; } else { if (strict) {//开启严格模式，没找到对应key值，抛出错误 throw new Error('please transfer a valid prop path to form item!'); } break; } } return { o: tempObj, //原始数据 k: keyArr[i], //key值 v: tempObj ? tempObj[keyArr[i]] : null // key值对应的值 }; };

function GetUrlParam(){ let url = document.location.toString(); let arrObj = url.split("?"); let params = Object.create(null) if (arrObj.length > 1){ arrObj = arrObj[1].split("&"); arrObj.forEach(item=>{ item = item.split("="); params[item[0]] = item[1] }) } return params; } // ?a=1&b=2&c=3 ==> {a: "1", b: "2", c: "3"}

function downloadFile(filename, data) { let DownloadLink = document.createElement('a'); if (DownloadLink) { document.body.appendChild(DownloadLink); DownloadLink.style = 'display: none'; DownloadLink.download = filename; DownloadLink.href = data; if (document.createEvent) { let DownloadEvt = document.createEvent('MouseEvents'); DownloadEvt.initEvent('click', true, false); DownloadLink.dispatchEvent(DownloadEvt); } else if (document.createEventObject) { DownloadLink.fireEvent('onclick'); } else if (typeof DownloadLink.onclick == 'function') { DownloadLink.onclick(); } document.body.removeChild(DownloadLink); } }

function toFullScreen() { let elem = document.body; elem.webkitRequestFullScreen ? elem.webkitRequestFullScreen() : elem.mozRequestFullScreen ? elem.mozRequestFullScreen() : elem.msRequestFullscreen ? elem.msRequestFullscreen() : elem.requestFullScreen ? elem.requestFullScreen() : alert("浏览器不支持全屏"); }

function exitFullscreen() { let elem = parent.document; elem.webkitCancelFullScreen ? elem.webkitCancelFullScreen() : elem.mozCancelFullScreen ? elem.mozCancelFullScreen() : elem.cancelFullScreen ? elem.cancelFullScreen() : elem.msExitFullscreen ? elem.msExitFullscreen() : elem.exitFullscreen ? elem.exitFullscreen() : alert("切换失败,可尝试Esc退出"); }

window.requestAnimationFrame = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.msRequestAnimationFrame || window.oRequestAnimationFrame || function (callback) { //为了使setTimteout的尽可能的接近每秒60帧的效果 window.setTimeout(callback, 1000 / 60); } window.cancelAnimationFrame = window.cancelAnimationFrame || window.webkitCancelAnimationFrame || window.mozCancelAnimationFrame || window.msCancelAnimationFrame || window.oCancelAnimationFrame || function (id) { //为了使setTimteout的尽可能的接近每秒60帧的效果 window.clearTimeout(id); }

function _isNaN(v){ return !(typeof v === 'string' || typeof v === 'number') || isNaN(v) }

function max(arr){ arr = arr.filter(item => !_isNaN(item)) return arr.length ? Math.max.apply(null, arr) : undefined } //max([1, 2, '11', null, 'fdf', []]) ==> 11

function min(arr){ arr = arr.filter(item => !_isNaN(item)) return arr.length ? Math.min.apply(null, arr) : undefined } //min([1, 2, '11', null, 'fdf', []]) ==> 1

function random(lower, upper) { lower = +lower || 0 upper = +upper || 0 return Math.random() * (upper - lower) + lower; } //random(0, 0.5) ==> 0.3567039135734613 //random(2, 1) ===> 1.6718418553475423 //random(-2, -1) ==> -1.4474325452361945

Object.keys = Object.keys || function keys(object) { if (object === null || object === undefined) { throw new TypeError('Cannot convert undefined or null to object'); } let result = []; if (isArrayLike(object) || isPlainObject(object)) { for (let key in object) { object.hasOwnProperty(key) && (result.push(key)) } } return result; }

Object.values = Object.values || function values(object) { if (object === null || object === undefined) { throw new TypeError('Cannot convert undefined or null to object'); } let result = []; if (isArrayLike(object) || isPlainObject(object)) { for (let key in object) { object.hasOwnProperty(key) && (result.push(object[key])) } } return result; }

Array.prototype.fill = Array.prototype.fill || function fill(value, start, end) { let ctx = this let length = ctx.length; start = parseInt(start) if(isNaN(start)){ start = 0 }else if (start < 0) { start = -start > length ? 0 : (length + start); } end = parseInt(end) if(isNaN(end) || end > length){ end = length }else if (end < 0) { end += length; } while (start < end) { ctx[start++] = value; } return ctx; } //Array(3).fill(2) ===> [2, 2, 2]

Array.prototype.includes = Array.prototype.includes || function includes(value, start) { let ctx = this; let length = ctx.length; start = parseInt(start) if(isNaN(start)) { start = 0 } else if (start < 0) { start = -start > length ? 0 : (length + start); } let index = ctx.indexOf(value); return index >= start; }

Array.prototype.find = Array.prototype.find || function find(fn, ctx) { ctx = ctx || this; let result; ctx.some((value, index, arr), thisValue) => { return fn(value, index, arr) ? (result = value, true) : false }) return result }

Array.prototype.findIndex = Array.prototype.findIndex || function findIndex(fn, ctx){ ctx = ctx || this let result; ctx.some((value, index, arr), thisValue) => { return fn(value, index, arr) ? (result = index, true) : false }) return result }

window.onload = function() { setTimeout(function() { let t = performance.timing; console.log('DNS查询耗时 ：' + (t.domainLookupEnd - t.domainLookupStart).toFixed(0)) console.log('TCP链接耗时 ：' + (t.connectEnd - t.connectStart).toFixed(0)) console.log('request请求耗时 ：' + (t.responseEnd - t.responseStart).toFixed(0)) console.log('解析dom树耗时 ：' + (t.domComplete - t.domInteractive).toFixed(0)) console.log('白屏时间 ：' + (t.responseStart - t.navigationStart).toFixed(0)) console.log('domready时间 ：' + (t.domContentLoadedEventEnd - t.navigationStart).toFixed(0)) console.log('onload时间 ：' + (t.loadEventEnd - t.navigationStart).toFixed(0)) if (t = performance.memory) { console.log('js内存使用占比：' + (t.usedJSHeapSize / t.totalJSHeapSize * 100).toFixed(2) + '%') } }) }

document.addEventListener('keydown', function(event) { return !( 112 == event.keyCode || //禁止F1 123 == event.keyCode || //禁止F12 event.ctrlKey && 82 == event.keyCode || //禁止ctrl+R event.ctrlKey && 18 == event.keyCode || //禁止ctrl+N event.shiftKey && 121 == event.keyCode || //禁止shift+F10 event.altKey && 115 == event.keyCode || //禁止alt+F4 "A" == event.srcElement.tagName && event.shiftKey //禁止shift+点击a标签 ) || （event.returnValue = false） });

['contextmenu', 'selectstart', 'copy'].forEach(function(ev) { document.addEventListener(ev, function(event) { return event.returnValue = false; }) });

function numAdd(num1, num2) { let baseNum, baseNum1, baseNum2; try { baseNum1 = num1.toString().split(".")[1].length; } catch (e) { baseNum1 = 0; } try { baseNum2 = num2.toString().split(".")[1].length; } catch (e) { baseNum2 = 0; } baseNum = Math.pow(10, Math.max(baseNum1, baseNum2)); return (num1 * baseNum + num2 * baseNum) / baseNum; };

function numSub(num1, num2) { let baseNum, baseNum1, baseNum2; let precision;// 精度 try { baseNum1 = num1.toString().split(".")[1].length; } catch (e) { baseNum1 = 0; } try { baseNum2 = num2.toString().split(".")[1].length; } catch (e) { baseNum2 = 0; } baseNum = Math.pow(10, Math.max(baseNum1, baseNum2)); precision = (baseNum1 >= baseNum2) ? baseNum1 : baseNum2; return ((num1 * baseNum - num2 * baseNum) / baseNum).toFixed(precision); };

function numMulti(num1, num2) { let baseNum = 0; try { baseNum += num1.toString().split(".")[1].length; } catch (e) { } try { baseNum += num2.toString().split(".")[1].length; } catch (e) { } return Number(num1.toString().replace(".", "")) * Number(num2.toString().replace(".", "")) / Math.pow(10, baseNum); };

function numDiv(num1, num2) { let baseNum1 = 0, baseNum2 = 0; let baseNum3, baseNum4; try { baseNum1 = num1.toString().split(".")[1].length; } catch (e) { baseNum1 = 0; } try { baseNum2 = num2.toString().split(".")[1].length; } catch (e) { baseNum2 = 0; } with (Math) { baseNum3 = Number(num1.toString().replace(".", "")); baseNum4 = Number(num2.toString().replace(".", "")); return (baseNum3 / baseNum4) * pow(10, baseNum2 - baseNum1); } };